onlyou2030的博客

题目： Given a string containing just the characters '(' and ')', find the length of the longest valid (well-formed) parentheses substring. For "(()", the longest valid parentheses substring is

问题描述： 有N件物品和一个容量为W的背包。第i件物品的重量是w[i]，价值是v[i]。求解将哪些物品装入背包可使这些物品的费用总和不超过背包容量，且价值总和最大。  这个问题的特点是：每种物品只有一件，可以选择放或者不放。 最优子结构：问题的最优解由相关子问题的最优解组合而成，而这些子问题可以独立求解。 关键问题：如何寻找一个最优子结构（子问题）？ 子问题：DP[i

题目： Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [−2,1,−3,4,−1,2,1,−5,4], the contiguous subarray [4,−

题目： A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to rea

题目： 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

题目： Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.) You have the following 3 operations permitt

题目： You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? 思路： 这题和前面Unique Path

题目： Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possible representation of s1 = "great": great /