题目传送门. 题意简述:将质数集合的所有子集按照子集和为第一关键字,字典序为第二关键字从小到大排序,求最终形成的字符串的第 \(l\sim r\) 个字符. 在 cnblogs 内查看. 又是一道妙妙题. 首先考虑当 \(r\leq 10^5\) 时直接搜索,首先枚举子集和 \(i\),状态是 \(sum,len,lim\) 表示剩余子集和为 \(sum\),大小为 \(len\),接下来只能使用第 \(lim\) 个及以后的质数.边界是 \(sum=0\),表示找到一个符合题意的子集. 直接暴…

Description: Count the number of prime numbers less than a non-negative number, n click to show more hints. References: How Many Primes Are There? Sieve of Eratosthenes Credits:Special thanks to @mithmatt for adding this problem and creating all test…

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. 译文: 10以下的素数之和为17,求出2000000以下的素数之和. ======================= 第一次code: import java.util.Scanner; public class Main { public static void main(String[]…

题目大家都非常熟悉,求小于n的所有素数的个数. 自己写的python 代码老是通不过时间门槛,无奈去看了看大家写的code.下面是我看到的投票最高的code: class Solution: # @param {integer} n # @return {integer} def countPrimes(self, n): if n < 3: return 0 primes = [True] * n primes[0] = primes[1] = False for i in range(2,…

examination questions Description: Count the number of prime numbers less than a non-negative number, n References: How Many Primes Are There? Sieve of Eratosthenes Please use the following function to solve the problem: int countPrimes(int n){ } 解题代…

Count Primes Description: Count the number of prime numbers less than a non-negative number, n click to show more hints. References: How Many Primes Are There? Sieve of Eratosthenes Credits: Special thanks to @mithmatt for adding this problem and cre…

Count the number of prime numbers less than a non-negative number, n public int countPrimes(int n) { ArrayList<Integer> primes = new ArrayList<Integer>(); ) , n - ); primes.add(); primes.add(); ; i <= n; i++) { boolean isPrime = true; for (…

http://acm.hdu.edu.cn/showproblem.php?pid=4715 Difference Between Primes Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Problem Description All you know Goldbach conjecture.That is to say, Every even integer great…

Difference Between Primes Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 3339    Accepted Submission(s): 953 Problem Description All you know Goldbach conjecture.That is to say, Every even int…

题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=4715 Difference Between Primes Description All you know Goldbach conjecture.That is to say, Every even integer greater than 2 can be expressed as the sum of two primes. Today, skywind present a new conje…