[LeetCode]112. Path Sum

[LeetCode]112. Path Sum

题目描述

思路

递归，计算每条路径的和，当前节点为叶子节点时，比较当前和与目标和
PS: 写成目标和减去节点值的方式，可以简化代码

代码

#include <iostream>

using namespace std;

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 == NULL)
            return false;

        path(root, root->val, sum);
        return res;
    }

    void path(TreeNode* root, int pathSum, int sum) {
        if (root->left == NULL && root->right == NULL && pathSum == sum)
            res = true;
        if (root->left)
            path(root->left, pathSum + root->left->val, sum);
        if (root->right)
            path(root->right, pathSum + root->right->val, sum);
    }
private:
    bool res = false;
};

int main() {
    TreeNode* n1 = new TreeNode(1);
    TreeNode* n2 = new TreeNode(2);
    TreeNode* n3 = new TreeNode(3);
    TreeNode* n4 = new TreeNode(4);

    n1->left = n2;
    //n1->right = n3;
    //n2->left = n4;

    Solution s;
    cout << s.hasPathSum(n1, 3) << endl;

    system("pause");
    return 0;
}