View Code of Problem 91

#include <cstdio>
#include <iostream>
#include <cmath>
using namespace std;
const int maxlen=1000;
bool isprime(int n){
	if(n==1){
		return false;
	}
	for(int i=2;i<=sqrt(n*1.0);i++){
		if(n%i==0)
			return false;
	}
	return true;
} 
int prime[maxlen]={};//开一千长的素数表 
int prinum=0;// 素数表长 
void printprime(){
	for(int i=1;i<=maxlen;i++){
		if(isprime(i)){
			prime[prinum++]=i;
		}
	}
}


int main(){
	int num;
	printprime();//
	cin>>num;
	cout<<num<<"=";
	int count=0;
	if(num==1){
		cout<<"1";
		return 0;
	}
	for(int i=0;i<maxlen&&prime[i]<=num;i++){
		while(num%prime[i]==0){
			if(count!=0)
				cout<<"*"<<prime[i];
			else
				cout<<prime[i];
			count++; 
			num/=prime[i];	
		}
	}
}