hdu 3199 Hamming Problem（构造？枚举？）

题意：

For each three prime numbers p1, p2 and p3, let's define Hamming sequence Hi(p1, p2, p3), i=1, ... as containing in increasing order all the natural numbers whose only prime divisors are p1, p2 or p3. 

For example, H(2, 3, 5) = 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 16, 18, 20, 24, 25, 27, ... 

So H5(2, 3, 5)=6.

给p1,p2,p3,n，求Hn(p1,p2,p3)

思路：

和humble numbers那题一样，，，看代码，，

代码：

int p1,p2,p3,x;
ll a[1000005];

int main(){

    while(scanf("%d%d%d%d",&p1,&p2,&p3,&x)!=EOF){
        if(p1>p2) swap(p1,p2);
        if(p1>p3) swap(p1,p3);
        if(p2>p3) swap(p2,p3);
        a[1]=1;
        int cn=1;
        while(cn<=x){
            ll temp;
            ll ans=INF;
            rep2(i,cn,1){
                temp=a[i]*p1;   if(temp>a[cn]) ans=min(ans,temp);
                temp=a[i]*p2;   if(temp>a[cn]) ans=min(ans,temp);
                temp=a[i]*p3;   if(temp>a[cn]) ans=min(ans,temp);
                if(temp<=a[cn]) break;
            }
            a[++cn]=ans;
        }
        printf("%I64d\n",a[cn]);
    }

    return 0;
}