leetcode20题解

题目描述

Given a string s containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[’ and ‘]’, determine if the input string is valid.

A...

leetcode19题解

题目

Given the head of a linked list, remove the nth node from the end of the list and return its head.

解题思路

虽然...

leetcode18题解

题目描述

Given an array nums of n integers, return an array of all the unique quadruplets [nums[a], nums[b], nums[c], nums[d]] such that:<...

leetcode17题解

题目描述

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Retu...

leetcode16题解

题目描述

Given an integer array of length and an integer , find three integers in such that the sum is closest to .numsntargetnumstarget Read More

leetcode15题解

题目描述

给定一个整数数组 nums，返回所有满足以下条件的三元组 [nums[i], nums[j], nums[k]]：

1. 索引 i、j、k 互不相等，即 i ≠ j、i ≠ k 且 j ≠ k；
2. 三个元素的和为...

leetcode13

描述

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an em...

Lecture3

自动机

• 一个有穷自动机可以接收$\epsilon$

  无穷自动机

• $\delta$: $Q \times \Sigma_\epsilon \to P(Q)$
• 幂级
...