PAT a1059题解

#include 
#include 

const int maxn = 100010;

bool isPrime(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 findPrime(){
	for(int i = 1; i < maxn; i++){
		if(isPrime(i)){
			prime[pNum++] = i;
		}
	}
}

struct factor{
	int x, cnt;
}fac[10];

int main(){
	findPrime();
	int n, num = 0;
	scanf("%d", &n);
	if(n == 1) printf("1=1");
	else{
		printf("%d=", n);
		int sqr = (int)sqrt(1.0 * n);
		for(int i = 0; i < pNum && prime[i] <= sqr; 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;
		}
		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;
}