Merge branch 'patch-1' of https://github.com/FreeJoker/leetcode-1 into FreeJoker-patch

haoel · haoel · commit 7268885dc8b6 · 2014-12-30T21:52:59.000+08:00
diff --git a/src/balancedBinaryTree/balancedBinaryTree.cpp b/src/balancedBinaryTree/balancedBinaryTree.cpp
@@ -24,28 +24,22 @@
 class Solution {
 public:
     bool isBalanced(TreeNode *root) {
-        if (root==NULL) return true;
-        
-        int left = treeDepth(root->left); 
-        int right = treeDepth(root->right);
-        
-        if (left-right>1 || left-right < -1) {
-            return false;
-        }
-        return isBalanced(root->left) && isBalanced(root->right);
+        int height=0;
+        return isBalancedUtil(root,&height);
     }
-    
-    int treeDepth(TreeNode *root) {
-        if (root==NULL){
-            return 0;
-        }
-        
-        int left=1, right=1;
-        
-        left += treeDepth(root->left);
-        right += treeDepth(root->right);
-        
-        return left>right?left:right;
+    bool isBalancedUtil(TreeNode* root,int *height){
+       if(root==NULL){
+          *height=0;
+          return 1;
+       }
+       int lh=0,rh=0;
+       bool isLeft,isRight;
+       isLeft=isBalancedUtil(root->left,&lh);
+       isRight=isBalancedUtil(root->right,&rh);
+       *height=(lh>rh?lh:rh)+1;
+       if(abs(lh-rh)>1)
+          return 0;
+       return isLeft&&isRight;
     }
 
 };
