# LeetCode 15. 3Sum

Description https://leetcode.com/problems/3sum/description/ Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the…

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Description https://leetcode.com/problems/3sum/description/ Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the…

Description https://leetcode.com/problems/unique-paths-ii/description/ Follow up for “Unique Paths”: Now consider if some obstacles are added to the grids. How many unique…

Description https://leetcode.com/problems/unique-paths/description/ A robot is located at the top-left corner of a m x n grid (marked ‘Start’ in the diagram below). The robot…

Description https://leetcode.com/problems/longest-palindromic-substring/description/ Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000.…

Description https://leetcode.com/problems/container-with-most-water/description/ Given n non-negative integers a1, a2, …, an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two…

Description https://leetcode.com/problems/trapping-rain-water/description/ Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water…

Description https://leetcode.com/problems/min-stack/description/ Design a stack that supports push, pop, top, and retrieving the minimum element in constant time. push(x) —…

Description https://leetcode.com/problems/sqrtx/description/ Implement int sqrt(int x). Compute and return the square root of x. x is guaranteed to be a non-negative integer. Example…

Description https://leetcode.com/problems/valid-parentheses/ Given a string containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[‘ and ‘]’, determine if the input…

Description https://leetcode.com/problems/string-to-integer-atoi/ Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you…