Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...) which sum to n.

Given strings S and T, find the minimum (contiguous) substring W of S, so that T is a subsequence of W.

Given n balloons, indexed from 0 to n-1. Each balloon is painted with a number on it represented by array nums. You are asked to burst all the balloons. If the you burst balloon i you will get nums[left] nums[i] nums[right] coins. Here left and right are adjacent indices of i. After the burst, th...

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.

LeetCode wants to give one of its best employees the option to travel among N cities to collect algorithm problems. But all work and no play makes Jack a dull boy, you could take vacations in some particular cities and weeks. Your job is to schedule the traveling to maximize the number of vacatio...

You are given coins of different denominations and a total amount of money amount. Write a function to compute the fewest number of coins that you need to make up that amount. If that amount of money cannot be made up by any combination of the coins, return -1.

In a given array nums of positive integers, find three non-overlapping subarrays with maximum sum.

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

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

Given a string, find length of the longest repeating subsequence such that the two subsequence don’t have same string character at same position, i.e., any ith character in the two subsequences shouldn’t have the same index in the original string.

A child is running up a staircase with n steps, and can hop either 1 step, 2 steps, or 3 steps at a time. Implement a method to count how many possible ways the child can run up the stairs.

Given n items with size Ai, an integer m denotes the size of a backpack. How full you can fill this backpack?

Given a sequence of integers, find the longest increasing subsequence (LIS).

The count-and-say sequence is the sequence of integers beginning as follows:

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.

Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate the number of 1's in their binary representation and return them as an array.

Given a positive integer n, break it into the sum of at least two positive integers and maximize the product of those integers. Return the maximum product you can get.

Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.

'?' Matches any single character.'*' Matches any sequence of characters (including the empty sequence).The matching should cover the entire input string (not partial).

A message containing letters from A-Z is being encoded to numbers using the following mapping:

The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that "all houses in this place forms a binary tree". It will automatic...

After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time, all houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, the security system ...

Given n distinct positive integers, integer k (k <= n) and a number target.

Given a string s, cut s into some substrings such that every substring is a palindrome.

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.

Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below.

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.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Now consider if some obstacles are added to the grids. How many unique paths would there be?