1059 Prime Factors（25 分）

Posted 2021-01-01 wanghao-boke

Given any positive integer N, you are supposed to find all of its prime factors, and write them in the format N = p?1???k?1????×p?2???k?2????×?×p?m???k?m????.

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 = p?1??^k?1??*p?2??^k?2??*…*p?m??^k?m??, where p?i??‘s are prime factors of N in increasing order, and the exponent k?i?? is the number of p?i?? -- hence when there is only one p?i??, k?i?? is 1 and must NOT be printed out.

Sample Input:

97532468

Sample Output:

97532468=2^2*11*17*101*1291

#include<cstdio>
#include<cmath>
const int maxn = 100010;

bool is_prime(int n){
    if(n == 1) return false;
    int sqr = (int)sqrt(1.0*n);
    for(int i = 2; i <= sqr; i++){
        if(n % i == 0) return false;
    }
    return true;
}

int prime[maxn],pNum = 0;
void Find_prime(){
    for(int i = 1 ; i < maxn; i++){
        if(is_prime(i) == true){
            prime[pNum++] = i;
        }
    }
}

struct facot{
    int x,cnt;
}fac[10];
int main(){
    Find_prime();
    int n;
    scanf("%d",&n);
    int num = 0;
    if(n == 1) printf("1=1");
    else{
        printf("%d=",n);
        int sqr = (int)sqrt(1.0*n);
        //printf("prime[0]");
        for(int i = 0; i < pNum ; i++){
            //printf("%d",i);
            if(n % prime[i] == 0){
                fac[num].x = prime[i];
                fac[num].cnt = 0;
            
            while(n % prime[i] == 0){
                fac[num].cnt++;
                n /= prime[i];
            }
            num++;
        }
        if(n == 1) break;
    }
    if(n != 1){
        fac[num].x = n;
        fac[num].cnt = 1;
    }
    //printf("1
");
    for(int i = 0; i < num; i++){
        if(i > 0) printf("*");
        printf("%d",fac[i].x);
        if(fac[i].cnt > 1) printf("^%d",fac[i].cnt);
    }
}
    return 0;
}