优先队列

http://www.cppblog.com/shyli/archive/2007/04/06/21366.html

stl中的优先队列的模板：

#include <queue> 

priority_queue <int> q;（队头为大，top为大）

这是按照从大到小的队列;

priority_queue<int, vector<int>, greater<int> > q;
这是从小到大的优先队列；

#include <queue> 

struct cmp 

{ 

    bool operator ()(const int &i,const int &j)

     {

        return i>j;

    } 

}; 

http://acm.sdut.edu.cn/sdutoj/problem.php?action=showproblem&problemid=2127

原来这题是优先队列

View Code

 1 #include<stdio.h>

 2 #include<queue>

 3 #include<vector>

 4 using namespace std;

 5 int main()

 6 {

 7     int n,i,j,a,b,s = 0,x;

 8     priority_queue<int, vector<int>, greater<int> > q;

 9     scanf("%d",&n);

10     for(i = 1 ; i <= n ; i++)

11     {

12         scanf("%d",&x);

13         q.push(x);

14     }

15     while(n>=2)

16     {

17         a = q.top();

18         q.pop();

19         b = q.top();

20         q.pop();

21         q.push(a+b);

22         s += a+b;

23         n--;

24     }

25     printf("%d\n",s);

26     return 0;

27 }

 

http://acm.hdu.edu.cn/showproblem.php?pid=4006

View Code

 1 #include<stdio.h>

 2 #include<queue>   

 3 #include<vector>  

 4 using namespace std;

 5 int q[10001],d;

 6 int main()

 7 {

 8     int i,j,n,k,a;

 9     char c;

10     while(scanf("%d%d",&n,&k)!=EOF)

11     {

12         priority_queue<int, vector<int>, greater<int> > q;

13         d = 0;

14         for(i = 1 ; i <= n ; i++)

15         {

16             scanf("%*c%c",&c);

17             if(c=='I')

18             {

19                 scanf("%d", &a);

20                 q.push(a);

21                 if(q.size()>k)

22                     q.pop();

23             }

24             else

25             if(c=='Q')

26                 printf("%d\n",q.top());

27         }

28     }

29     return 0;

30 }

 http://acm.hdu.edu.cn/showproblem.php?pid=4302两个优先队列 实现左右优先吃

View Code

  1 #include<stdio.h>

  2 #include<string.h>

  3 #include<queue>

  4 #include<vector>

  5 #include<stdlib.h>

  6 int k[100005],w[100005];

  7 using namespace std;

  8 int main()

  9 {

 10     int i,j,a,b,t,n,d,f,g,x,y = 0;

 11     char c[30],num[10];

 12     long s;

 13     scanf("%d",&t);

 14     while(t--)

 15     {

 16         y++;

 17         scanf("%d%d%*c",&d,&n);    

 18         b = 0;

 19         s = 0;

 20         priority_queue <int> q1;

 21         priority_queue<int, vector<int>, greater<int> > q2;

 22         for(i = 1 ;i <= n ; i++)

 23         {

 24             gets(c);

 25             f = 0;

 26             g = 0;

 27             int f1 = 0;

 28             for(j = 0; j < strlen(c) ; j++)

 29             {

 30                 if(c[j]==' ')

 31                  f = 1;

 32                 if(f&&c[j]!=' ')

 33                 {

 34                     f1 = 1;

 35                     num[g++] = c[j]; 

 36                 }

 37             }

 38             if(f1)

 39             {

 40                 num[g] = '\0';

 41                 a = atol(num);

 42                 if(a>b)

 43                     q2.push(a);

 44                 else

 45                     q1.push(a);

 46             }

 47             else

 48             {

 49                 if(q1.size()&&q2.size())

 50                 {

 51                     if(b-q1.top()>q2.top()-b)

 52                     {

 53                         x = 1;

 54                         s+=q2.top()-b;

 55                         b = q2.top();

 56                         q2.pop();

 57                     }

 58                     else if(b-q1.top()<q2.top()-b)

 59                     {

 60                         x = 0;

 61                         s+=b-q1.top();

 62                         b = q1.top();

 63                         q1.pop();

 64                     }

 65                     else

 66                     {

 67                         if(x)

 68                         {

 69                             x = 1;

 70                             s+=q2.top()-b;

 71                             b = q2.top();

 72                             q2.pop();

 73                         }

 74                         else

 75                         {

 76                             x = 0;

 77                             s+=b-q1.top();

 78                             b = q1.top();

 79                             q1.pop();

 80                         }

 81                     }

 82                 }

 83                 else if(q1.size())

 84                 {

 85                         x = 0;

 86                         s+=b-q1.top();

 87                         b = q1.top();

 88                         q1.pop();

 89                 }

 90                 else if(q2.size())

 91                 {

 92                     x = 1;

 93                     s+=q2.top()-b;

 94                     b = q2.top();

 95                     q2.pop();

 96                 }

 97             }

 98         }

 99         printf("Case %d: ",y);

100         printf("%ld\n",s);

101     }

102     return 0;

103 }