poj 1338 Ugly Numbers

 原题链接：http://poj.org/problem?id=1338

优先队列的应用，如下：

 1 #include<cstdio>

 2 #include<cstdlib>

 3 #include<queue>

 4 #include<functional>

 5 #include<iostream>

 6 #include<algorithm>

 7 using namespace std;

 8 typedef long long ll;

 9 const int Max_N = 1510;

10 ll ans[Max_N];

11 void init(){

12     int arr[4] = { 2, 3, 5 };

13     priority_queue<ll, vector<ll>, greater<ll> > que;

14     que.push(1);

15     for (int i = 1; i <= 1500;){

16         ll t = que.top();

17         que.pop(), ans[i] = t;

18         if (ans[i] == ans[i - 1]){

19             continue;

20         } else {

21             i++;

22         }

23         for (int j = 0; j < 3; j++) que.push((ll)(t * arr[j]));

24     }

25 }

26 int main(){

27     init();

28     int n;

29     while (~scanf("%d", &n) && n) printf("%lld\n", ans[n]);

30     return 0;

31 }

View Code