LeetCode-Path Sum

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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.

Solution:

Code:

<span style="font-size:14px;">/** * 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 helper(TreeNode *root, const int &sum, int tempSum) {        if (!root) return false;        tempSum += root->val;        if (tempSum == sum && !root->left && !root->right) return true;        if (!root->left && !root->right) return false;        if (helper(root->left, sum, tempSum)) return true;        if (helper(root->right, sum, tempSum)) return true;        return false;    }        bool hasPathSum(TreeNode *root, int sum) {        return helper(root, sum, 0);        }};</span>

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