1059 Prime Factors (25 分)(素数表的建立)【回顾】
Given any positive integer N, you are supposed to find all of its prime factors, and write them in the format N = p1^k1 * p2^k2 …pm^km.
Input Specification:
Each input file contains one test case which gives a positive integer N in the range of long int.
Output Specification:
Factor N in the format N = p1^k1 * p2^k2 …pm^km, where pi's are prime factors of N in increasing order, and the exponent ki is the number of pi -- hence when there is only one pi, ki is 1 and must NOT be printed out.
Sample Input:
97532468
Sample Output:
97532468=2^2*11*17*101*1291
题目大意:
给出一个整数,按照从小到大的顺序输出其分解为质因数的乘法算式
分析:
根号int的最大值不会超过50000,先建立个50000以内的素数表,然后从2开始一直判断是否为它的素数,如果是就将a=a/i继续判断i是否为a的素数,判断完成后输出这个素数因子和个数,用state判断是否输入过因子,输入过就要再前面输出。
原文链接:https://blog.csdn.net/liuchuo/article/details/52261852
题解
#include
using namespace std;
const int maxn=100010;
//判断n是否为素数
bool is_prime(int n)
{
if(n==1)
return false;
for(int i=2; i*i<=n; i++)
{
if(n%i==0)
return false;
}
return true;
}
int prime[maxn],pNum=0;
//求素数表
void Find_Prime()
{
for(int i=1; i0)
printf(" *");="" printf("%d",fac[i].x);="" if(fac[i].cnt="">1)
printf("^%d",fac[i].cnt);
}
return 0;
}