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LeetCode: 113. Path Sum II

fbd4ffd0717b 2022-12-06 阅读 61


LeetCode: 113. Path Sum II

题目描述

Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

5
/ \
4 8
/ / \
11 13 4
/ \ / \
7 2 5 1

return

[
[5,4,11,2],
[5,8,4,5]
]

解题思路

深度搜索遍历所有的路径,记录和为 sum 的路径。

AC 代码

/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
private:
void pathSumRef(TreeNode* root, int sum, vector<int>& path, vector<vector<int>>& paths)
{
if(root == nullptr) return;
if(root->left == nullptr && root->right == nullptr && sum == root->val)
{
path.push_back(root->val);
paths.push_back(path);
path.pop_back();
}
else if(root->left == nullptr && root->right == nullptr)
{
return;
}
else
{
path.push_back(root->val);
pathSumRef(root->left, sum - root->val, path, paths);
pathSumRef(root->right, sum - root->val, path, paths);
path.pop_back();
}
}
public:
vector<vector<int>> pathSum(TreeNode* root, int sum) {
if(root == nullptr) return {};
vector<vector<int>> paths;
vector<int> path;

pathSumRef(root, sum, path, paths);

return paths;
}
};


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