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  • [LeetCode] 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:
        int target = 0;
        bool search(TreeNode *cur, int curSum)
        {
            if(cur == NULL) return false;
            curSum += cur -> val;
            if(curSum == target && cur -> left == NULL && cur -> right == NULL) return true;
            return search(cur -> left, curSum) || search(cur -> right, curSum);
        }
        bool hasPathSum(TreeNode *root, int sum) {
            // IMPORTANT: Please reset any member data you declared, as
            // the same Solution instance will be reused for each test case.
            if(root == NULL) return false;
            target = sum;
            return search(root, 0);
        }
    };
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  • 原文地址:https://www.cnblogs.com/changchengxiao/p/3419341.html
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