首页 > 代码库 > Path Sum

Path Sum

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.

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    bool hasPathSum(TreeNode *root, int sum) {        bool flag = false;        level(root,0,sum,flag);        return flag;    }    void level(TreeNode *node, int tmpsum, int sum, bool& flag)  {        if(flag) return;        if(node == NULL) return;        int newsum = tmpsum + node->val;        if(newsum == sum && node->left == NULL && node->right == NULL){            flag = true;            return;        }        else{            level(node->left, newsum, sum, flag);            level(node->right, newsum, sum, flag);        }    }};

 

Path Sum