The xor-longest Path Time Limit: 2000MS Memory Limit: 65536K Total Submissions: 10038 Accepted: 2040 Description In an edge-weighted tree, the xor-length of a path p is defined as the xor sum of the weights of edges on p: ⊕ is the xor operator. W…
We know that the longest path problem for general case belongs to the NP-hard category, so there is no known polynomial time solution for it. However, for a special case which is directed acyclic graph, we can solve this problem in linear time. First…
We all know that the shortest path problem has optimal substructure. The reasoning is like below: Supppose we have a path p from node u to v, another node t lies on path p: u->t->v ("->" means a path). We claim that u->t is also a sh…
题目来源 https://leetcode.com/problems/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. 题意分析 Input: a binary tree, sum Output: list of list. Conditions: 给定一个二叉树,将所有root-leaf的路径值和等于sum的路径返…
题目来源 https://leetcode.com/problems/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. 题意分析 Input: a binary tree, sum Output: True or False Con…
题目来源 https://leetcode.com/problems/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…
题目来源 https://leetcode.com/problems/unique-paths-ii/ Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in the g…
