add shortest distance

Author: jyxia

Easy/100-sameTree.js

@@ -10,10 +10,14 @@
  * @param {TreeNode} q
  * @return {boolean}
  */
- var isSameTree = function(p, q) {
-     if (!p && !q) return true;
-     if (p && q && p.val === q.val) {
-         if (isSameTree(p.left, q.left) && isSameTree(p.right, q.right)) return true;
-     }
-     return false;
- };
+var isSameTree = function(p, q) {
+    if (!p || !q) {
+        return p === q;
+    }
+
+    if (p.val === q.val) {
+        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+    }
+
+    return false;
+};

Easy/101-symmetricTree.js

@@ -33,6 +33,21 @@ var helper = function(left, right) {
     return false;
 }
 
+// third try
+var helper = function(left, right) {
+    if (!left && !right) {
+        return true;
+    } else if (!left || !right) {
+        return false;
+    } else {
+        if (left.val === right.val) {
+            return isSymmetricHelper(left.left, right.right) && isSymmetricHelper(left.right, right.left);
+        } else {
+            return false;
+        }
+    }
+}
+
 // iterative
 var isSymmetric = function(root) {
     if (!root) return true;

Easy/160-IntersectionofTwoLinkedLists.js

@@ -94,7 +94,7 @@ var getIntersectionNode = function(headA, headB) {
         pa = pa.next;
         pb = pb.next;
         if (pa === pb) {
-           return pa ;
+           return pa;
         }
 
         if (!pa) {

Easy/243-shortestWordDist.js

@@ -0,0 +1,33 @@
+/**
+* question: http://www.programcreek.com/2014/08/leetcode-shortest-word-distance-java/
+*
+*/
+
+function shortestWordDist(words, word1, word2) {
+  var index1, index2;
+  var dist = Math.pow(2, 32) - 1; // for some reason in JavaScript, manually set max.
+
+  words.forEach(function(word, index) {
+    if (word === word1) {
+      index1 = index;
+    }
+
+    if (word === word2) {
+      index2 = index;
+    }
+
+    if (index1 >= 0 && index2 >= 0) {
+      dist = Math.min(Math.abs(index1 - index2), dist);
+    }
+  })
+
+  return dist;
+}
+
+// test cases
+var words = ["practice", "makes", "perfect", "coding", "makes"];
+var word1 = 'practice';
+var word2 = 'coding';
+var word3 = 'makes';
+console.log(shortestWordDist(words, word1, word2));
+console.log(shortestWordDist(words, word2, word3));

Medium/236-lcaBinaryTree.js

@@ -0,0 +1,30 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {TreeNode}
+ */
+var lowestCommonAncestor = function(root, p, q) {
+    if (!root || root === p || root === q) {
+        return root;
+    }
+
+    var left = lowestCommonAncestor(root.left, p, q);
+    var right = lowestCommonAncestor(root.right, p, q);
+
+    if (!left) {
+        return right;
+    }
+    if (!right) {
+        return left;
+    }
+    
+    return root;
+};

Medium/244-shortestWordDistII.js

@@ -0,0 +1,48 @@
+/**
+* question: http://www.programcreek.com/2014/07/leetcode-shortest-word-distance-ii-java/
+*
+*/
+
+function ShortestWordDist(words) {
+  this.hashMap = {};
+
+  var map = this.hashMap;
+
+  words.forEach(function(word, index) {
+    if (word in map) {
+      map[word].push(index);
+    } else {
+      map[word] = [index];
+    }
+  });
+}
+
+ShortestWordDist.prototype.shortest = function(word1, word2) {
+  var list1 = this.hashMap[word1];
+  var list2 = this.hashMap[word2];
+  var dist = Math.pow(2, 32) - 1;
+
+  for (var i = 0, j = 0; i < list1.length && j < list2.length;) {
+    var index1 = list1[i];
+    var index2 = list2[j];
+
+    dist = Math.min(Math.abs(index1 - index2), dist);
+    if (index1 < index2) {
+      i++;
+    } else {
+      j++;
+    }
+  }
+
+  return dist;
+};
+
+// test cases
+var ws = ["practice", "makes", "perfect", "coding", "makes", "google", "coding", "apple", "alpha"];
+var words = new ShortestWordDist(ws);
+
+var word1 = 'practice';
+var word2 = 'coding';
+var word3 = 'apple';
+console.log(words.shortest(word1, word2));
+console.log(words.shortest(word2, word3));

README.md

@@ -165,6 +165,7 @@
 * [221. Maximal Square](https://leetcode.com/problems/maximal-square/) - [Solution](./Medium/221-maximalSquare.js)
 * [229. Majority Element II](https://leetcode.com/problems/majority-element-ii/) - [Solution](./Medium/229-majorityElementII.js)
 * [230. Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst/) - [Solution](./Medium/230-kthSmallestElementinBST.js)
+* [236. Lowest Common Ancestor of a Binary Tree](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/) - [Solution](./Medium/236-lcaBinaryTree.js)
 * [238. Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/) - [Solution](./Medium/238-productExceptSelf.js)
 * [240. Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/) - [Solution](./Medium/240-Search2DMatrixII.js)
 * [241. Different Ways to Add Parentheses](https://leetcode.com/problems/different-ways-to-add-parentheses/) - [Solution](./Medium/241-differentWaysAddParentheses.js)