[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.

/** * 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) {        if (!root)    {    return false;    }    return DFS(root,0,sum);    }private:    bool DFS(TreeNode * Node, int last, int sum)    {    int curSum = last + Node->val;    if (!Node->left && !Node->right && curSum == sum)    {    return true;    }        if (Node->left!=NULL && DFS(Node->left,curSum,sum))    {    return true;    }    if (Node->right!=NULL && DFS(Node->right,curSum,sum))    {    return true;    }    return false;    }};

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