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题目解析:(链接)
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.
解题思路：
深度优先搜索
1 /** 2 * Definition for a binary tree node. 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 dfs(TreeNode *root, int sum, int cur_sum) { 13 if (!root) { 14 return false; 15 } 16 17 if (root->left == nullptr && root->right == nullptr) { 18 return sum == cur_sum + root->val; 19 } 20 21 return dfs(root->left, sum, cur_sum + root->val) || dfs(root->right, sum, cur_sum + root->val); 22 } 23 24 bool hasPathSum(TreeNode* root, int sum) { 25 return dfs(root, sum, 0); 26 } 27 };
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原文地址：http://www.cnblogs.com/skycore/p/5014457.html
