Merge branch 'FreeJoker-patch'

Author: haoel

src/balancedBinaryTree/balancedBinaryTree.cpp

@@ -22,6 +22,30 @@
  * };
  */
 class Solution {
+public:
+    bool isBalanced(TreeNode *root) {
+        int height=0;
+        return isBalancedUtil(root, height);
+    }
+
+    bool isBalancedUtil(TreeNode* root, int& height){
+       if(root==NULL){
+          height=0;
+          return true;
+       }
+       int lh=0, rh=0;
+       bool isLeft = isBalancedUtil(root->left, lh);
+       bool isRight = isBalancedUtil(root->right, rh);
+       height = (lh > rh ? lh : rh) + 1;
+       return (abs(lh-rh)<=1 && isLeft && isRight);
+    }
+
+};
+
+//Notes: 
+// I think the above solution should be more efficent than the below, 
+//  but for leetcode, the below solution needs 60ms, the above needs 88ms
+class Solution {
 public:
     bool isBalanced(TreeNode *root) {
         if (root==NULL) return true;
@@ -39,7 +63,7 @@ class Solution {
         if (root==NULL){
             return 0;
         }
-        
+
         int left=1, right=1;
 
         left += treeDepth(root->left);