Articles
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Best Time to Buy and Sell Stock IV
Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most k transactions.
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123 - Best Time to Buy and Sell Stock III
Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete at most two transactions.
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122 - Best Time to Buy and Sell Stock II
Say you have an array for which the ith element is the price of a given stock on day i. Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times). However, you may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).
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121 - Best Time to Buy and Sell Stock
Say you have an array for which the ith element is the price of a given stock on day i. If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.
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Longest Common Subsequence
Given two strings, find the longest common subsequence (LCS). Your code should return the length of LCS.
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139 - Word Break
Given a string s and a dictionary of words dict, determine if s can be break into a space-separated sequence of one or more dictionary words.
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55 - Jump Game
Given an array of non-negative integers, you are initially positioned at the first index of the array. Each element in the array represents your maximum jump length at that position. Determine if you are able to reach the last index.
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70 - Climbing Stairs
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?
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63 - 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 grid.
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62 - Unique Paths
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 reach the bottom-right corner of the grid (marked ‘Finish’ in the diagram below). How many possible unique paths are there?
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64 - 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.
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Backpack II
Given n items with size Ai and value Vi, and a backpack with size m. What’s the maximum value can you put into the backpack?
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Backpack
Given n items with size Ai, an integer m denotes the size of a backpack. How full you can fill this backpack?
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120 - Triangle
Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.
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60 - Permutation Sequence
Given n and k, return the k-th permutation sequence. Reference
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40 - Combination Sum II
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 combination.
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39 - Combination Sum
Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T. The same repeated number may be chosen from C unlimited number of times.
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77 - Combinations
Given two integers n and k, return all possible combinations of k numbers out of 1 … n.
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95 - Unique Binary Search Trees II
Given n, generate all structurally unique BST’s (binary search trees) that store values 1…n.
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47 - Permutations II
Given a list of numbers with duplicate number in it. Find all unique permutations.
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46 - Permutations
Given a list of numbers, return all possible permutations.
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90 - Subsets II
Given a list of numbers that may has duplicate numbers, return all possible subsets.
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78 - Subsets
Given a set of distinct integers, return all possible subsets.
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20 - Valid parentheses
Given a string s containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[’ and ‘]’, determine if the input string is valid.
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Unique Characters
Implement an algorithm to determine if a string has all unique characters.
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Singleton
Singleton is a most widely used design pattern. If a class has and only has one instance at every moment, we call this design as singleton. For example, for class Mouse (not a animal mouse), we should design it in singleton. You job is to implement a getInstance method for given class, return the same instance of this class every time you call this method.
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7 - Reverse Integer
Reverse digits of an integer.
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131 - Palindrome Partitioning
Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s.
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305 - Number of Islands II
Given a n,m which means the row and column of the 2D matrix and an array of pair A( size k). Originally, the 2D matrix is all 0 which means there is only sea in the matrix. The list pair has k operator and each operator has two integer A[i].x, A[i].y means that you can change the grid matrix[A[i].x][A[i].y] from sea to island. Return how many island are there in the matrix after each operator.
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200 - Number of Islands
Given a boolean 2D matrix, find the number of islands.
