pengweixuan008的博客

题目：Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every eleme

题目：Count the number of prime numbers less than a non-negative number, n.代码：public class Solution {    public int countPrimes(int n) {        boolean [] a = new boolean[n];        int cou

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equ

public class Solution {    public int romanToInt(String s) {        char[] symbol = { 'I', 'V', 'X', 'L', 'C', 'D', 'M' };        int[] val = { 1, 5, 10, 50, 100, 500, 1000 };        Map map =