算法入门经典P120（greater）

 

#include<iostream>
#include<set>
#include<vector>
#include<queue>
using namespace std;

typedef long long LL;
int coeff[3] = {2,3,5};
int main(){
    priority_queue<LL,vector<LL>,greater<LL> >pq;
    set<LL>s;
    pq.push(1);
    s.insert(1);
    for(int i=1;;i++){
        LL x = pq.top();pq.pop();
        if(i==1500){
            cout<<x<<endl;
            break;
        }
        for(int j=0;j<3;j++){
            LL x2 = x*coeff[j];
            if(!s.count(x2)){
                s.insert(x2);
                pq.push(x2);
            }
        }
    }
    return 0;
}

greater反义：less