Merge pull request Hearen#100 from DuanSky22/master

week 11 done.

Author: Hearen

DuanShikai/week11-12/_025_Reverse_Nodes_in_k_Group.java

@@ -0,0 +1,46 @@
+package com.sky.leetcode;
+/**
+ * @author DuanSky
+ * @date 2016年3月17日 下午1:12:03
+ * @content 
+ */
+
+public class _025_Reverse_Nodes_in_k_Group {
+	
+	public static void main(String args[]){
+		_025_Reverse_Nodes_in_k_Group test = new _025_Reverse_Nodes_in_k_Group();
+		ListNode head = ListNode.generate(new int[]{1,2});
+		int k = 2;
+		ListNode t = test.reverseKGroup(head, k);
+	}
+	
+	
+	public ListNode reverseKGroup(ListNode head, int k) {
+		if(head == null || head.next == null) return head; //至少需要两个元素才有翻转的必要
+        ListNode  lastTail = new ListNode(0), res = lastTail,thisNext = null, nextHead = head, curr = head;
+        while(curr != null){
+        	int counter = 1; 
+        	while(nextHead != null && counter < k) { //记录需要反转的链表
+        		nextHead = nextHead.next;
+        		counter ++;
+        	} 
+        	ListNode thisHead = curr;
+        	if( nextHead != null && counter == k){ //需要反转
+        		nextHead = nextHead.next;
+        		ListNode thisTail = null;
+        		while(curr!=nextHead){
+        			thisNext = curr.next;
+        			curr.next = thisTail;
+        			thisTail = curr;
+        			curr = thisNext;
+        		}
+        		lastTail.next = thisTail;
+        		lastTail = thisHead;
+        	}else{
+        		lastTail.next = thisHead;
+        		break;
+        	}
+        }
+        return res.next;
+    }
+}

DuanShikai/week11-12/_133_Clone_Graph.java

@@ -0,0 +1,60 @@
+package com.sky.leetcode;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * @author DuanSky
+ * @date 2016年3月18日 下午9:15:20
+ * @content 
+ */
+
+public class _133_Clone_Graph {
+	
+	public static void main(String args[]){
+		_133_Clone_Graph test = new _133_Clone_Graph();
+		UndirectedGraphNode node  = new UndirectedGraphNode(0);
+		node.neighbors.add(node);
+		node.neighbors.add(node);
+		test.cloneGraph(node);
+	}
+	
+	
+	public UndirectedGraphNode cloneGraph(UndirectedGraphNode node){
+        if(node == null) return null; //MISTAKE 注意需要考虑为空的情况
+		return core(node,new HashMap<Integer,UndirectedGraphNode>());
+	}
+	
+	public UndirectedGraphNode core(UndirectedGraphNode node, Map<Integer,UndirectedGraphNode> map){
+		if(map.containsKey(node.label)) return map.get(node.label); //如果之前新建的这样的一个对象，则直接返回这个对象
+		UndirectedGraphNode copy = new UndirectedGraphNode(node.label);
+		map.put(copy.label, copy);
+		List<UndirectedGraphNode> neighbors = node.neighbors;
+		for(UndirectedGraphNode neighbor : neighbors){
+			copy.neighbors.add(core(neighbor,map));
+		}  
+		return copy;
+	}
+	
+	//====================================================================================
+	public UndirectedGraphNode cloneGraph_wrong_answer(UndirectedGraphNode node) {
+        if(node == null) return null;
+		List<UndirectedGraphNode> neighbors = node.neighbors;
+		List<UndirectedGraphNode> copy = new ArrayList<UndirectedGraphNode>();
+		for(UndirectedGraphNode neighbor : neighbors){
+			copy.add(cloneGraph_wrong_answer(neighbor)); //MISTAKE 当出现环路的时候，会陷入死循环。
+		}
+		UndirectedGraphNode root = new UndirectedGraphNode(node.label);
+		root.neighbors = copy;
+		return root;
+    }
+
+}
+
+class UndirectedGraphNode {
+	 int label;
+	 List<UndirectedGraphNode> neighbors;
+	 UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
+}

DuanShikai/week11-12/_210_Course_Schedule_II.java

@@ -0,0 +1,55 @@
+package com.sky.leetcode;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+/**
+ * @author DuanSky
+ * @date 2016年3月18日 下午4:07:49
+ * @content 
+ */
+
+public class _210_Course_Schedule_II {
+	
+	public static void main(String args[]){
+		_210_Course_Schedule_II test = new _210_Course_Schedule_II();
+		int numCourses = 2;
+		int[][] prerequisites = {};
+		int[] res = test.findOrder(numCourses, prerequisites);
+	}
+	
+	public int[] findOrder(int numCourses, int[][] prerequisites) {
+        int[][] matrix = new int[numCourses][numCourses];
+        int[] indegree = new int[numCourses];
+        
+        for(int i = 0; i < prerequisites.length; i++){
+        	int from = prerequisites[i][0], to = prerequisites[i][1];
+        	if(matrix[to][from]==0) indegree[from]++;
+        	matrix[to][from] = 1;
+        }
+        
+        int counter = -1;
+        Queue<Integer> queue = new LinkedList<Integer>();
+        int[] res = new int[numCourses];
+        
+        for(int i = 0; i < numCourses; i++){
+        	if(indegree[i]==0) queue.add(i);
+        }
+        
+        while(!queue.isEmpty()){
+        	counter ++;
+        	int curr = queue.poll();
+			res[counter] = curr;
+        	for(int i = 0; i < numCourses; i++){
+        		if(matrix[curr][i]==1){
+        			if(--indegree[i]==0){
+
+        				queue.add(i);
+        			}
+        		}
+        	}
+        }
+        return counter+1 == numCourses ? res : new int[0];
+    }
+
+}

DuanShikai/week11-12/_336_Palindrome_Pairs.java

@@ -0,0 +1,106 @@
+package com.sky.leetcode;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * @author DuanSky
+ * @date 2016年3月16日 下午7:36:01
+ * @content 
+ */
+
+public class _336_Palindrome_Pairs {
+	
+	
+	public static void main(String args[]){
+		_336_Palindrome_Pairs test = new _336_Palindrome_Pairs();
+		String s = "abcdefdcba";
+		String[] words = {"aihhieeegdebhb","acajjajbbibaab","ddjihhebahcead","cehdaiaeaggai","di","bcacdfjadgfjgiicghc","ddhigcdidggfcejib","djbgdcadgiaaieh","fggfdajadcfhajhag","dfahbdjcbgdf","dfbhhdfjdcfefij","fjgbegdifedgf","ffeice","gdgjcaichica","gigjifehagcacggg","ehjgha","ddj","igffdiddgecidcjfj","cca","heeig","cdghidigcgdaeda","jbbachabahheidacd","feahagifaacejg","abdbgidheigfcabffe","ehcbieidgfagijafd","gcji","f","jddgd","ibachgei","eeabadcbiebdchiaha","baejcdeef","cagbjjhaecgi","ijfcfecdccchee","jhiidcdba","dgdibjihcbbhg","fcibbcbbjhhbiiiaag","fggefjgbjdajcbcgjbj","gg","hhadjfeaa","aghbgcjfcdcihfc","bfffcggfeddeajbhafge","dggfafhafc","dcdbhcifbbbgbcaeh","dacacdhbjd","ghhifd","aabifcjhadibhfdjbga","baejceehiagaabchabff","bjagbabf","hgijgdifccjdehjaccbf","gbfejbfddgcja","iiedgaigdg","eeieg","cei","bchicbfcihbcjejjfg","jhjdfi","ebdgaghfbjhfceh","bdjdgegfdddadiieaici","abeecj","g","jcadaigbcabcggeddjcd","h","ajjg","iebcbgfbjhbfbai","ghj","gidafdigfgfcjfg","hgjacihicbcfifghgcbc","gaaibecj","ifjciedfgdegfi","bfcbdddjfjjhfahbjfaa","fafgijfgahf","gcjacdbgdbecghif","gjdgah","fdbbcbidbhbgf","ghihccifb","ghjeecjgfefd","b","egigbdaicefieddicee","gjg","baae","jeiehgccjefedjib","jjcjgeaajcj","ihjbhbjgejgcheb","accce","jhc","gjj","icaadccfihj","bafefdchbhibibdfggg","egehfbegjedcicdfjfge","fbcdighdcieideh","bjfibbjigc","daidhjjb","aeeec","ed","dgdbjjibccjdafh","bbde","biejhahgd","bjhhdiidcbe","dibceifgj","c","hedi","fjjfihdejifjfba","hd","bffbd","gdjaaaaihgbiahicde","gdehfchcd","icgidjcj","gd","jddfjhcgiefjee","daajiighijhdfbi","bggj","ecgfbahaacfiajc","ggdffajibaidjib","jf","fhicadfghdcchiiifj","aji","gfjacgcfbicgdjad","cfhfcggadigidigihdid","bfcdidiifgfbc","ahiidhjhbfdiahic","edecdcd","cigigjfafdbhbdhhhjf","fbjefgghghcheja","dhcheddfjffeejb","ffcd","ificcdfdb","ghjgafhiffdcgghjja","jgfadaecjgh","fifahiijidjgcdiedee","dccejgdfaggdadfccd","aeghbjdjgifah","gejaehchdfhfdeegie","bafa","aebgccebdfcgc","abdgbcg","dcedgfjbbgc","jbfhaddbbdaiiegjic","jegdijdaebj","ejgajggidiahadgddeab","ece","i","hegjjfbgegijdjgb","aiiee","eefad","cdbeifbfa","afej","hagaadb","egfdib","hfaiididcidfjccf","debf","ddhceh","hjgecgjjihf","fjjfj","gjceffcedjff","aaaghiabbdagbchhg","dgaieejgbfjdhcbcijfa","cacf","cbjbijehadihhjdi","fiabgiiccbba","eagi","edaagghhehgddic","egcaghjcfci","cjbhgfbdfddh","jbjdhghgjjjacgidfbeg","icjihhgeffbhihhdh","caceeibgbihcfidbig","efij","ahjgfdegbig","cieifgigjdbje","iebahhbjjbjiegaca","bjiheaiaacajdjbdbe","gbgbcdge","bdaijhgefjibfhcedc","gjgfbhhdedhb","hedbgdbajfg","eiebdiiedhagad","a","digcdgjejhf","aaiafddgcefj","dhba","d","ag","bbchdccbgjfbjcgfci","afg","cbjgjfffj","ccgifgeccjgc","jhbgb","dfggiifehbf","hfhedbgjdhfghgdja","fagjbdge","cejhjbccgjggihcgeaf","dbhbfebffgaf","cdhdjhcj","hacjbaifjb","gjejjbbbecidahjched","jadfiigjidfgfa","efjggaebaa","heieaihfffj","ejeafadace","jfajijdifijacbhjc","fig","cehegedcdjcijehaeac","dgjeijfae","dcbeddfdb","gdd","ad","eafdbedfdgeiiif","dagihgebabiahhaf","fiifhdbfhhbb","dfc","eajigcfifjjdhdhjadf","egccbbhgddggebehebhc","debahdfadag","fhhcedjachdcjhd","iaaicjbgejjaihcdaab","jggbiee","gigdjccjficebidhjdcj","fa","aehaghjbfibcd","ceiicfbfgccbfjbi","ieheijg","bhcffafei","ahhihfjja","bdiihbciicfbhead","bebihe","dedigbeddahabdfa","dcehfcbhibiihhg","bdbdaifcbediabebhee","ghbgecjcidafbgfad","bfiaafcbdijj","jffeijjijcbeihgbccfj","fafbbjgagjbdd","jcejgd","dffgjfdibfabjgddcb","acdhaebbiiacffgcdj","ifibah","fighebjccg","jehejgdgiddebehfhdba","ffebafcaafcgadfjai","icjcdgachddebbbhj","hcchjbecfigah","cdjfffgafhie","fedaejjeedahhccg","gdedhijcjh","aaccbgifg","dibffhffigaeegfg","ba","hg","efa","acifijeg","cichjibjdhgajcdc","ccejgejcgabafgb","dhfi","cdgdfcfbhaefbdddh","aebdjf","fdghbigifah","jeegcicbfejc","bebehc","dgfgdhg","jjfbifgfj","gejbebejbfhb","ghfhheeaddc","iedah","hfjchb","hjhdfbjfigdbgbgggf","ebfiecdghcfg","eheiicbhiedi","fjaa","ccbeheejcicahhhj","ebbjbd","hafebbhfgdjbde","aibjfcfe","jbbdbjac","ghdaec","gbabhj","e","fcbjgibadfcdbd","afahbhjjbad","adadeiibjgchihgcdfjh","dgadgfji","ecidcfhajhdfcf","dfeeebggedhfidede","cadejafjaajaicd","ibd","dagf","eigfajhfgdcbhi","ce","jdbgiefed","bgffchfeebhejgh","fj","geddhdghcb","jcabjacjhbiejjaehih","gfchcjceadifii","cgjjaai","jicfgjciciihagd","agcheaeahddheje","jaaiehdhfhcbg","ciafhfadeahiedgac","fdecghgehfdigfa","hajffedb","hcjefhfeggbaafgcheh","fdddcdchbhjgfig","aghggjdcbehgccd","ehfdj","gbbgdb","cdgjifidcdiejfga","gbjdi","fegicbfdhbdeicdac","ijfbegfdjcbjcaddbcgg","hihfjdadifh","fdccdcdchdh","ciciaejifbeefcciigb","afcccc","jfci","fccje","fd","ebbgfdi","bdcig","ehbaji","cbdjiffgfagagjbaid","bejhcgdcaeaaibibca","fhigfbfddfbai","cgbadcgdchia","jh","aahjbj","fddfahebabfajafgceb","cbficcbhadchedcidg","iihjdaedbb","bbigheagfee","ffggehgfificifdejga","acidhghj","bbbggfegjh","bfcbhdied","bejadihbdjid","ajhfgjehaaabb","fhgjjedajhb","jejghcjfbgda","ef","jdcahjiahgfejaacc","fjacgcjjfeb","ggefjf","jfejaah","fbgfhefcegcbbihf","igefidejfgdefjeg","beaecfgjcda","dffccaecieicbcgheeeh","hbfaebjdi","eddgcfjhbh","ieheecbefgjhcjficb","ia","iibfefchhdei","fjdcdccaefi","gebcjejihhdjjbf","jgee",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+		System.out.println(test.palindromePairs_1(words));
+	}
+
+	//my solution. 
+	public List<List<Integer>> palindromePairs_1(String[] words) {
+	    List<List<Integer>> res = new LinkedList<>();
+	    if (words == null) return res;
+	    Map<String,Integer> map = new HashMap<>();
+	    for(int i = 0; i < words.length; i ++) map.put(words[i], i);
+	    for(int i = 0; i < words.length; i ++){
+	    	int l = 0, r = 0; // l 和 r 分别是左边界和右边界，这两个值只有一个为0，不可能同时为0。l为0时，是固定左边部分
+	    	while(l <= r){ //需要循环取出所有的情况
+	    		String s = words[i].substring(l,r);
+	    		Integer j = map.get(new StringBuilder(s).reverse().toString()); //MISTAKE 注意这里需要反转
+		    	if(j!=null  && i!=j && isPalindrome(words[i].substring(l == 0 ? r : 0, l == 0 ? words[i].length() : l))) //MISTAKE 注意这里需要考虑i!=j，因为不能自己跟自己组成回文
+		    		res.add(Arrays.asList(l == 0 ? new Integer[]{i,j} : new Integer[]{j,i}));
+		    	if(r < words[i].length()) r++; //r先加到右边界
+		    	else l++; //l在加到左边界
+	    	}
+	    }
+	    return res;
+	} 
+	
+	//beautiful solution. 
+	public List<List<Integer>> palindromePairs_(String[] words) {
+	    List<List<Integer>> pairs = new LinkedList<>();
+	    if (words == null) return pairs;
+	    HashMap<String, Integer> map = new HashMap<>();
+	    for (int i = 0; i < words.length; ++ i) map.put(words[i], i);
+	    for (int i = 0; i < words.length; ++ i) {
+	        int l = 0, r = 0;
+	        while (l <= r) {
+	            String s = words[i].substring(l, r);
+	            Integer j = map.get(new StringBuilder(s).reverse().toString());
+	            if (j != null && i != j && isPalindrome(words[i].substring(l == 0 ? r : 0, l == 0 ? words[i].length() : l)))
+	                pairs.add(Arrays.asList(l == 0 ? new Integer[]{i, j} : new Integer[]{j, i}));
+	            if (r < words[i].length()) ++r;
+	            else ++l;
+	        }
+	    }
+	    return pairs;
+	}
+	
+	//暴力检测 68ms 未通过
+	public List<List<Integer>> palindromePairs(String[] words) {
+        List<List<Integer>> res = new ArrayList<>();
+        for(int i = 0; i < words.length; i++){
+        	for(int j = i + 1; j < words.length; j++){
+        		if(!canMakePalindrome(words[i]+words[j])) continue;
+        		if(isPalindrome(words[i]+words[j]))
+        			res.add(Arrays.asList(new Integer[]{i,j}));
+        		if(isPalindrome(words[j]+words[i]))
+        			res.add(Arrays.asList(new Integer[]{j,i}));
+        	}
+        }
+        return res;
+    }
+	
+	//判断一个字符串是否可以构成回文
+	private boolean isPalindrome(String s) {
+		if(s == null || s.length() < 2) return true;
+		int i = 0, j = s.length()-1;
+		while(i<j){
+			if(s.charAt(i)!=s.charAt(j)) return false;
+			i++; j--;
+		}
+		return true;
+	}
+
+	//判断原字符串是否可以通过改变元素顺序构成回文
+	public boolean canMakePalindrome(String s){
+		if(s==null || s.length()<2) return true;
+		Set<Character> set = new HashSet<Character>();
+		for(int i = 0; i < s.length(); i++){
+			char a = s.charAt(i);
+			if(set.contains(a)) set.remove(a);
+			else set.add(a);
+		}
+		return set.size()<=1;
+	}
+
+}