[CPP] 110. Balanced Binary Tree

Author: UnresolvedCold

cpp/110-Balanced-Binary-Tree.cpp

@@ -0,0 +1,28 @@
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    
+    int getHeight(TreeNode* root, unordered_map<TreeNode*, int>& umap) {
+        if (root==NULL) return 0;
+        if (umap.find(root) != umap.end()) return umap[root];
+        int res = max(getHeight(root->left, umap), getHeight(root->right, umap))+1;
+        umap[root] = res;
+        return res;
+    }
+    bool isBalanced(TreeNode* root) {
+        unordered_map<TreeNode*, int> umap;
+        if (root == NULL) return true;
+        if (abs(getHeight(root->left, umap) - getHeight(root->right, umap)) > 1) return false;
+        return isBalanced(root->left) && isBalanced(root->right);
+    }
+};