leetcode

Author: springuper

generateParenthesis.js

@@ -0,0 +1,34 @@
+'use strict';
+
+/**
+ * @param {number} n
+ * @returns {string[]}
+ */
+var generateParenthesis = function (n) {
+    var list = [];
+    var generate = function (open, close, str) {
+        if (open > close) return;
+        if (open == 0 && close == 1) {
+            list.push(str + ')');
+            return;
+        }
+        if (open > 0) {
+            generate(open - 1, close, str + '(');
+        }
+        if (close > 0) {
+            generate(open, close - 1, str + ')');
+        }
+
+    };
+    generate(n - 1, n, '(');
+    return list;
+};
+
+var assert = require('assert');
+assert.deepEqual(generateParenthesis(3), [
+    "((()))",
+    "(()())",
+    "(())()",
+    "()(())",
+    "()()()"
+]);

swapPairs.js

@@ -0,0 +1,52 @@
+'use strict';
+
+/**
+ * Definition for singly-linked list.
+ */
+function ListNode(val) {
+   this.val = val;
+   this.next = null;
+}
+
+/**
+ * @param {ListNode} head
+ * @returns {ListNode}
+ */
+var swapPairs = function (head) {
+    var ahead = new ListNode(null);
+    ahead.next = head;
+    var a = ahead;
+    var b = head;
+    var c = b && b.next
+    if (!b || !c) return head;
+    // update head
+    head = c;
+
+    while (true) {
+        b.next = c.next;
+        a.next = c;
+        c.next = b;
+        // update a, b, and c
+        a = b;
+        b = b.next;
+        c = b && b.next;
+        if (!b || !c) break;
+    }
+    return head;
+};
+
+var assert = require('assert');
+
+var a = new ListNode('a');
+var b = new ListNode('b');
+var c = new ListNode('c');
+var d = new ListNode('d');
+a.next = b;
+b.next = c;
+c.next = d;
+var list = swapPairs(a);
+console.log(list.next.val);
+assert(list.val === 'b');
+assert(list.next.val === 'a');
+assert(list.next.next.val === 'd');
+assert(list.next.next.next.val === 'c');