priority_queue 丑数 2 3 5

还可以用指针++
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include<string.h>
#include <algorithm>
#include <queue>
using namespace std;
#define ll long long
priority_queue<ll,vector<ll>,greater<ll> > pi;
int main(  )
{
    

    //freopen("in.txt","r",stdin);
    int i,j,before,zero,n,k,p2,p3,p5;
    ll a[1501],temp;
    p2=p3=p5=1;
    a[1]=1;j=1;
    pi.push(1);before=0;
    while( j<= 1500 )
    {
        temp=pi.top();
        pi.pop();
        if(temp!=before)
        {
         
            a[j++]=temp;
          pi.push(temp*2);
          pi.push(temp*3);
          pi.push(temp*5);
          before=temp;
        }
        
    }
 
    while(scanf("%d",&n)!=EOF)
        printf("%lld\n",a[n]);
    
    return 0;
}