leetCode(40):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.

搜索支路的方法

/**
 * 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 {
public:
    bool findPath(TreeNode* root, int nowSum,const int sum)
    {
    	nowSum += root->val;//当前值

        //假设已经是叶子结点,且和相等,则直接返回真
    	if (!root->left && !root->right && nowSum == sum)
    		return true;

    	bool found_left = false;
    	bool found_right = false;

    	if (root->left)	//左子树不为空。则在左子树中搜索
    		found_left = findPath(root->left, nowSum, sum);

    	if (!found_left && root->right)	//假设左子树没找到,则在右子树中搜索
    		found_right = findPath(root->right, nowSum, sum);	

    	return found_left || found_right;//仅仅要在一条支中上找到则返回真
    }

    bool hasPathSum(TreeNode* root, int sum) {
        if (root == NULL)
		    return false;
	    findPath(root, 0, sum);
    }
};
时间: 2024-10-13 23:34:41

leetCode(40):Path Sum的相关文章

【Leetcode】Path Sum II

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] ] 思路:与[Leetcode]Path Sum 不同

LeetCode:Path Sum - 树的根节点到叶节点的数字之和

1.题目名称 Path Sum(树的根节点到叶节点的数字之和) 2.题目地址 https://leetcode.com/problems/path-sum/ 3.题目内容 英文: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. 中文:给定一颗二叉树,如

LeetCode "Minimum Path Sum" - 2D DP

An intuitive 2D DP: dp[i][j] = min(grid[i-1][j-1] + dp[i-1][j], grid[i-1][j-1] + dp[i][j+1]) class Solution { public: int minPathSum(vector<vector<int> > &grid) { // dp[i][j] = min(dp[i-1][j] + dp[i][j], dp[i][j-1] + dp[i][j]); int n = gri

【LeetCode】Path Sum

题目 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,

Leetcode:Minimum Path Sum 矩形网格最小路径和

Minimum Path Sum: Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or right at any point in time. 解题分析: 每次只能向下或者向

[leetcode]Minimum Path Sum @ Python

原题地址:https://oj.leetcode.com/problems/minimum-path-sum/ 题意: Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path. Note: You can only move either down or r

leetcode -day17 Path Sum I II &amp; Flatten Binary Tree to Linked List &amp; Minimum Depth of Binary Tree

1.  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 r

[array] leetcode - 40. Combination Sum II - Medium

leetcode - 40. Combination Sum II - Medium descrition Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. Each number in C may only be used once in the combinat

[LeetCode] 437. Path Sum III_ Easy tag: DFS

You are given a binary tree in which each node contains an integer value. Find the number of paths that sum to a given value. The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to