A1059 Prime Factors (25 分)

#include <iostream>
#include <math.h>
using namespace std;

struct factor{
  int x, cnt; //x为质因子，cnt为该质因子的个数 
}fac[10];

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

int main(int argc, char** argv) {
  
  long long int n;
  cin >> n;
  
  if(n == 1){
    cout << "1=1" << endl;
    return 0;
  }  
  cout << n << "=";
  
  int sqr = (int)sqrt(n*1.0);
  int count = 0;
  for(int i = 0; i <= sqr; i++){
    if(isPrime(i) == true){
      if(n % i == 0){ //如果是他的因子 
        fac[count].x = i;
        fac[count].cnt = 0;
        while(n % i == 0){
          fac[count].cnt++;
          n /= i;
        }
        count++;
      }
    }
  }
  
  if(n != 1){
    fac[count].x = n;
    fac[count++].cnt = 1;
  }
 
  for(int i = 0; i < count; i++){
    if(i > 0) cout << "*";
    cout << fac[i].x ;
    if(fac[i].cnt > 1){
      cout << "^" << fac[i].cnt;
    }
  }
  
  return 0;
}