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
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 1 #include <iostream> 2 #include <cmath> 3 using namespace std; 4 const int maxn=100005; 5 int prime[maxn],pnum=0; 6 bool p[maxn]={0}; 7 void Find_Prime(){ 8     p[0]=p[1]=true; 9     for(int i=2;i<maxn;i++){10         if(p[i]==false){11             prime[pnum++]=i;12             for(int j=i+i;j<maxn;j+=i)13                 p[j]=true;14         }15     }16 }17 struct factor{18     int x,cnt;19 }fac[20];20 int num;21 void PrimeFactor(int n){22     int sqr=(int)sqrt(n);23     num=0;24     for(int i=0;i<maxn && prime[i]<=sqr;i++){25         if(n%prime[i]==0){26             fac[num].x=prime[i];27             fac[num].cnt=0;28             while(n%prime[i]==0){29                 fac[num].cnt++;30                 n/=prime[i];31             }32             num++;33         }34         if(n==1) break;35     }36     if(n!=1){37         fac[num].x=n;38         fac[num++].cnt=1;39     }40 }41 void Print_fac(int n){42     printf("%d=",n);43     for(int i=0;i<num;i++){44         if(i>0)45             printf("*");46         if(fac[i].cnt>1)47             printf("%d^%d",fac[i].x,fac[i].cnt);48         else49             printf("%d",fac[i].x);50     }51     printf("\n");52 }53 int main()54 {55     Find_Prime();56     int n;57     while(scanf("%d",&n)!=EOF){58         if(n==1)59             printf("1=1\n");60         else{61             PrimeFactor(n);62             Print_fac(n);63         }64 65         /*66         int a=(1<<31)-1;67         cout<<a<<endl;68         cout<<"1"<<endl;69         PrimeFactor(a);70         cout<<"2"<<endl;71         Print_fac(a);72         cout<<"3"<<endl;73         cout<<num<<endl;74         */75     }76     return 0;77 }78 //97532468=2^2*11*17*101*1291