Treeland consists of n cities and n−1 roads. Each road is bidirectional and connects two distinct cities. From any city you can get to any other city by roads. ...

A superhero fights with a monster. The battle consists of rounds, each of which lasts exactly nn minutes. After a round ends, the next round starts immediately....

首先递推公式 ： 钱币面值 从 1，一直遍历到 n , 然后兑换的面值从 j=1 到 j 等于最大的面值， 面对 第 i种面值的硬币，有两种选择，不选则当前硬币面值的所有情况 加上选择当前面值的...

An array of integers p1,p2,…,pnp1,p2,…,pn is called a permutation if it contains each number from 11 to nn exactly once. For example, the following arrays are p...

Given an array of non-negative integers, you are initially positioned at the first index of the array.

Say you have an array for which the ith element is the price of a given stock on day i.

Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

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

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 ...

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob...