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hua Lhua L
hua L
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hua L
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week6
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‎LiangJianhua/task6/BinaryTreeZigzagLevelOrderTraversal.java‎

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package com.josh.task6;
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import java.util.ArrayList;
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import java.util.List;
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import org.junit.Test;
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public class BinaryTreeZigzagLevelOrderTraversal {
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//初始化二叉树
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public TreeNode iniBinaryTree(){
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TreeNode node1 = new TreeNode(3);
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TreeNode node2 = new TreeNode(9);
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TreeNode node3 = new TreeNode(20);
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TreeNode node4 = new TreeNode(15);
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TreeNode node5 = new TreeNode(7);
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node1.left = node2;
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node1.right = node3;
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node2.left = null;
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node2.right = null;
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node3.left = node4;
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node3.right = node5;
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node4.left = null;
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node4.right = null;
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node5.left = null;
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node5.right = null;
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return node1;
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}
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@Test
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public void test(){
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TreeNode root = iniBinaryTree();
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List<List<Integer>> list = new ArrayList<List<Integer>>();
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list = zigzagLevelOrder(root);
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for(int i=0;i<list.size();i++){
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System.out.print("第"+(i+1)+"层元素： ");
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for(int j=0;j<list.get(i).size();j++){
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System.out.print(list.get(i).get(j)+" ");
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}
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System.out.println();
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}
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}
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public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
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List<List<Integer>> list = new ArrayList<List<Integer>>();
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int depath = getMaxDepth(root);
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for(int i=1;i<depath+1;i++){
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List<Integer> levelList = new ArrayList<Integer>();
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transLevel(root,i,levelList);
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if(i%2 == 0){//反序输出
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List<Integer> afterSortList = new ArrayList<Integer>();
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for(int k=levelList.size()-1;k>=0;k--){
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afterSortList.add(levelList.get(k));
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}
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list.add(afterSortList);
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}else{//顺序输出
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list.add(levelList);
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}
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}
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return list;
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}
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//打印二叉树某一层的节点
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public void transLevel(TreeNode root, int level,List<Integer> list){
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if(root==null)
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return;
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else{
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if(level == 1){
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list.add(root.val);
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}else{
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transLevel(root.left, level-1,list);
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transLevel(root.right, level-1,list);
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}
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}
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}
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//得到二叉树最大高度
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public int getMaxDepth(TreeNode root) {
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if(root == null) return 0;
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else{
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int left = getMaxDepth(root.left);
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int right = getMaxDepth(root.right);
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return 1+Math.max(left, right);
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}
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}
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}

‎LiangJianhua/task6/ConstructBinaryTreeFromPreorderAndInorderTraversal.java‎

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package com.josh.task6;
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import java.util.ArrayDeque;
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import java.util.Queue;
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import org.junit.Test;
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public class ConstructBinaryTreeFromPreorderAndInorderTraversal {
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@Test
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public void test(){
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int[] preorder = {1,2,3,4,5,6,7,8};
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int[] inorder = {3,2,5,4,1,7,6,8};
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//TreeNode root = getTree(preorder,0,7,inorder,0,7);
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TreeNode root = buildTree(preorder, inorder);
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//层次遍历构造的二叉查找树树
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Queue<TreeNode> queue = new ArrayDeque<TreeNode>();
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queue.add(root);
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while(!queue.isEmpty()){
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TreeNode curNode = queue.remove();
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int e = curNode.val;
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System.out.print(e+" ");
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if(curNode.left != null) queue.add(curNode.left);
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if(curNode.right != null) queue.add(curNode.right);
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}
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}
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public TreeNode buildTree(int[] preorder, int[] inorder) {
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if(preorder.length==0 || inorder.length==0 || preorder.length!=inorder.length) return null;
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if(preorder.length==1) return new TreeNode(preorder[0]);
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return getTree(preorder, 0, preorder.length-1, inorder, 0, inorder.length-1);
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}
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//根据先序和中序构造二叉树
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public TreeNode getTree(int[] preorder,int p_s,int p_e, int[] inorder,int i_s,int i_e){
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if(i_s<=i_e){
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int rootPos = getRootPosFromInorder(inorder, i_s, i_e, preorder[p_s]);
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int len = rootPos - i_s;
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TreeNode root = new TreeNode(-1);
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root.val = inorder[rootPos];
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root.left = getTree(preorder, p_s+1, p_s+len, inorder, i_s, rootPos-1);
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root.right = getTree(preorder, p_s+len+1, p_e, inorder, rootPos+1, i_e);
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return root;
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}
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return null;
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}
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//根据先序中的第一个位置，及当前根curRootPos,遍历在中序中的位置，进而将中序分为左右两部分
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public int getRootPosFromInorder(int[] inorder,int i_s,int i_e,int curRootPos){
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for(int i=i_s;i<=i_e;i++){
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if(inorder[i] == curRootPos)
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return i;
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}
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return -1;
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}
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}

‎LiangJianhua/task6/ConvertSortedListToBinarySearchTree.java‎

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package com.josh.task6;
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import java.util.ArrayDeque;
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import java.util.Queue;
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import org.junit.Test;
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public class ConvertSortedListToBinarySearchTree {
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public ListNode iniListNode(){
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ListNode head = new ListNode(1);
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ListNode listNode2 = new ListNode(2);
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ListNode listNode3 = new ListNode(3);
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ListNode listNode4 = new ListNode(4);
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ListNode listNode5 = new ListNode(5);
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ListNode listNode6 = new ListNode(6);
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ListNode listNode7 = new ListNode(7);
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head.next = listNode2;
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listNode2.next = listNode3;
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listNode3.next = listNode4;
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listNode4.next = listNode5;
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listNode5.next = listNode6;
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listNode6.next = listNode7;
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listNode7.next = null;
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return head;
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}
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@Test
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public void test(){
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ListNode head = iniListNode();
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TreeNode root = sortedListToBST(head);
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//层次遍历构造的二叉查找树树
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Queue<TreeNode> queue = new ArrayDeque<TreeNode>();
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queue.add(root);
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while(!queue.isEmpty()){
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TreeNode curNode = queue.remove();
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int e = curNode.val;
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System.out.print(e+" ");
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if(curNode.left != null) queue.add(curNode.left);
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if(curNode.right != null) queue.add(curNode.right);
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}
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}
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public TreeNode sortedListToBST(ListNode head) {
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if(head==null) return null;
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if(head.next==null) return new TreeNode(head.val);
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int count = 1;
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ListNode tempCount = head;
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while(tempCount.next != null){//计算ListNode长度
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count ++;
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tempCount = tempCount.next;
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}
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int[] num = new int[count];
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int i=0;
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while(head.next != null){//ListNode转化为num数组
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num[i] = head.val;
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i++;
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head = head.next;
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}
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num[i] = head.val;
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TreeNode root = getMidNode(0, num.length-1, num);//构造二叉搜索树
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TreeNode last = new TreeNode(num[num.length-1]);//添加最后一个元素
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TreeNode tempNode = root;
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while(tempNode.right !=null){
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tempNode = tempNode.right;
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}
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tempNode.right = last;
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return root;
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}
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//递归-根据有序数组构造二叉查找树
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public TreeNode getMidNode(int s,int e,int[] num){
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TreeNode root = new TreeNode(-1);
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if(s<e){
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int mid = (s+e)/2;
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root.val = num[mid];
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root.left = getMidNode(s, mid, num);
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root.right = getMidNode(mid+1, e, num);
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return root;
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}
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return null;
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}
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}

‎LiangJianhua/task6/ListNode.java‎

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package com.josh.task6;
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public class ListNode {
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int val;
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ListNode next;
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ListNode(int x) {
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val = x;
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}
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}

‎LiangJianhua/task6/PopulatingNextRightPointersInEachNodeII.java‎

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package com.josh.task6;
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import java.util.ArrayList;
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import java.util.List;
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import org.junit.Test;
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public class PopulatingNextRightPointersInEachNodeII {
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//初始化二叉树
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public TreeLinkNode iniTreeLinkNode(){
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TreeLinkNode node1 = new TreeLinkNode(3);
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TreeLinkNode node2 = new TreeLinkNode(9);
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TreeLinkNode node3 = new TreeLinkNode(20);
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TreeLinkNode node4 = new TreeLinkNode(15);
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TreeLinkNode node5 = new TreeLinkNode(7);
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node1.left = node2;
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node1.right = node3;
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node2.left = null;
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node2.right = null;
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node3.left = node4;
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node3.right = node5;
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node4.left = null;
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node4.right = null;
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node5.left = null;
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node5.right = null;
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return node1;
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}
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@Test
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public void test(){
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TreeLinkNode root = iniTreeLinkNode();
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// List<TreeLinkNode> list = new ArrayList<TreeLinkNode>();
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// transLevel(root, 2, list);
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connect(root);
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// for(int i=0;i<list.size();i++){
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// System.out.println(list.get(i).val);
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// }
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}
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public void connect(TreeLinkNode root) {
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if(root == null) return;
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int depath = getMaxDepth(root);
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for(int i=1;i<depath+1;i++){
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List<TreeLinkNode> list = new ArrayList<TreeLinkNode>();
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transLevel(root,i, list);
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int count = 0;
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while(count<list.size()-1){
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list.get(count).next = list.get(count+1);
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count++;
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}
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list.get(count).next = null;
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//test
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// TreeLinkNode head = list.get(0);
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// while(head.next !=null){
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// System.out.print(head.val+" ");
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// head = head.next;
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// }
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// System.out.println(head.val+" ");
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}
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}
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//打印二叉树某一层的节点
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public void transLevel(TreeLinkNode root, int level,List<TreeLinkNode> list){
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if(root==null)
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return;
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else{
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if(level == 1){
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list.add(root);
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}else{
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transLevel(root.left, level-1,list);
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transLevel(root.right, level-1,list);
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}
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}
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}
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//得到二叉树最大高度
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public int getMaxDepth(TreeLinkNode root) {
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if(root == null) return 0;
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else{
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int left = getMaxDepth(root.left);
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int right = getMaxDepth(root.right);
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return 1+Math.max(left, right);
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}
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}
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}

‎LiangJianhua/task6/TreeLinkNode.java‎

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package com.josh.task6;
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public class TreeLinkNode {
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int val;
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TreeLinkNode left, right, next;
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TreeLinkNode(int x) { val = x; }
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}

‎LiangJianhua/task6/TreeNode.java‎

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package com.josh.task6;
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public class TreeNode {
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int val;
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TreeNode left;
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TreeNode right;
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TreeNode(int x) { val = x; }
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}

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