PAT 1059. Prime Factors (25) 质因子分解

题目链接 http://www.patest.cn/contests/pat-a-practise/1059

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 *…*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 = p₁^k₁ * p₂^k₂ *…*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.（坑爹，这最后一句不是说满足情况不输出，可答案是要输出的，害我吓考虑2个case没过）

Sample Input:

97532468

Sample Output:

97532468=2^2*11*17*101*1291
---------------------------------------------------华丽的分割线---------------------------------------------------------------------------------------------

 #include <iostream>
 #include <cmath>
 using namespace std;
 const int maxn=;
 int prime[maxn],pnum=;
 bool p[maxn]={};
 void Find_Prime(){
     p[]=p[]=true;
     for(int i=;i<maxn;i++){
         if(p[i]==false){
             prime[pnum++]=i;
             for(int j=i+i;j<maxn;j+=i)
                 p[j]=true;
         }
     }
 }
 struct factor{
     int x,cnt;
 }fac[];
 int num;
 void PrimeFactor(int n){
     int sqr=(int)sqrt(n);
     num=;
     for(int i=;i<maxn && prime[i]<=sqr;i++){
         if(n%prime[i]==){
             fac[num].x=prime[i];
             fac[num].cnt=;
             while(n%prime[i]==){
                 fac[num].cnt++;
                 n/=prime[i];
             }
             num++;
         }
         if(n==) break;
     }
     if(n!=){
         fac[num].x=n;
         fac[num++].cnt=;
     }
 }
 void Print_fac(int n){
     printf("%d=",n);
     for(int i=;i<num;i++){
         if(i>)
             printf("*");
         if(fac[i].cnt>)
             printf("%d^%d",fac[i].x,fac[i].cnt);
         else
             printf("%d",fac[i].x);
     }
     printf("\n");
 }
 int main()
 {
     Find_Prime();
     int n;
     while(scanf("%d",&n)!=EOF){
         if(n==)
             printf("1=1\n");
         else{
             PrimeFactor(n);
             Print_fac(n);
         }

         /*
         int a=(1<<31)-1;
         cout<<a<<endl;
         cout<<"1"<<endl;
         PrimeFactor(a);
         cout<<"2"<<endl;
         Print_fac(a);
         cout<<"3"<<endl;
         cout<<num<<endl;
         */
     }
     return ;
 }
 //97532468=2^2*11*17*101*1291