Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.
For example:
Given the below binary tree
and sum = 22,
5
/ 4 8
/ / 11 13 4
/ \ 7 2 1
return true, as there exist a root-to-leaf
path 5->4->11->2 which sum is 22.
水！
1 /** 2 * Definition for binary tree 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 bool hasPathSum(TreeNode *root, int sum) { 13 if (root == NULL) { 14 return false; 15 } 16 if (root->left == NULL && root->right == NULL) { 17 return root->val == sum; 18 } 19 bool flag1 = hasPathSum(root->left, sum - root->val); 20 bool flag2 = hasPathSum(root->right, sum - root->val); 21 return flag1 || flag2; 22 } 23 };
[Leetcode] Path Sum,布布扣,bubuko.com
原文：http://www.cnblogs.com/easonliu/p/3634955.html