分解质因数

Smith Numbers http://poj.org/problem?id=1142 http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=133

#include<cstdio>
int fac[128];
int find_fac(int n){//对n分解质因数，返回质因数个数
    int cnt=0;
    for(int i=2;i*i<=n;i+=2){
        while(!(n%i)){
            n/=i;
            fac[cnt++]=i;
        }
        if(i==2) i--;
    }
    if(n>1) fac[cnt++]=n;
    return cnt;
}
int div(int x){
    int res=0;
    while(x){
        res+=x%10;
        x/=10;
    }
    return res;
}
bool judge(int n){
    int lf=find_fac(n);
    if(lf==1) return false;
    int sum=0;
    for(int i=0;i<lf;i++){
        sum+=div(fac[i]);
    }
    if(sum==div(n)) return true;
    return false;
}
int main(){
    int n;
    while(~scanf("%d",&n),n){
        while(!judge(++n));
        printf("%d
",n);
    }
    return 0;
}

 Perfection http://poj.org/problem?id=1528

求所有除数的和

#include<cstdio>
int ds_func(int n){//求n所有除数的和
    int ret=1,m=n,t;
    for(int i=2;i*i<=n;i+=(i==2)?1:2){
        if(!(n%i)){
            t=i*i;
            n/=i;
            while(!(n%i)){
                t*=i;
                n/=i;
            }
            ret*=(t-1)/(i-1);
        }
    }
    return n>1?ret*(n+1):ret;
}
int main() {
    int n;
    puts("PERFECTION OUTPUT");
    while(~scanf("%d",&n),n){
        printf("%5d",n);
        int sum=ds_func(n);
        if(sum>n+n) puts("  ABUNDANT");
        else if(sum==n+n) puts("  PERFECT");
        else puts("  DEFICIENT");
    }
    puts("END OF OUTPUT");
    return 0;
}

end