Balanced Binary Tree
描述
Given a binary tree, determine if it is height-balanced.
For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the
two subtrees of every node never differ by more than 1.
1 #include <cstdlib> 2 #include <iostream> 3 4 struct TreeNode{ 5 int val; 6 TreeNode* left; 7 TreeNode* right; 8 TreeNode(int x):val(x),left(nullptr),right(nullptr){} 9 }; 10 11 class Solution { 12 public: 13 bool isBalanced(TreeNode* root) { 14 int depth=0; 15 return helper(root,depth); 16 } 17 bool helper (TreeNode* root,int& depth) { 18 if (root == nullptr){ 19 depth = 0; 20 return true; 21 } 22 int ld,rd; 23 if(helper(root->left,ld) && helper(root->right,rd)){ 24 if(abs(ld-rd)>1){ 25 return false; 26 } 27 depth = ld>rd? ld+1 : rd+1; 28 } 29 } 30 }; 31 32 /** 33 Function:compute the depth of a binary tree. 34 */ 35 36 int treeDepth(TreeNode* root) 37 { 38 if(!root) return 0; 39 int ld = treeDepth(root->left); 40 int rd = treeDepth(root->right); 41 return ld > rd ? ld + 1 : rd + 1; 42 } 43 44 int main() 45 { 46 TreeNode* root = new TreeNode(1); 47 root->left = new TreeNode(2); 48 root->right = new TreeNode(5); 49 root->left->right = new TreeNode(3); 50 root->left->right->right = new TreeNode(4); 51 52 Solution s; 53 s.isBalanced(root); 54 std::cout << treeDepth(root) << std::endl; 55 56 return 0; 57 }