Cleaning Shifts（POJ 2376 贪心）

 1 #include <iostream>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <cstdio>
 5 using namespace std;
 6 struct node
 7 {
 8     int x,y;
 9 }cow[25000+5];
10 int cmp(node a,node b)
11 {
12     if(a.x==b.x)    return a.y>=b.y;
13     return a.x<b.x;
14 }
15 int main()
16 {
17     int T,N;
18     int i,j;
19     freopen("in.txt","r",stdin);
20     while(scanf("%d%d",&N,&T)!=EOF)
21     {
22         for(i=0;i<N;i++)
23             scanf("%d%d",&cow[i].x,&cow[i].y);
24         sort(cow,cow+N,cmp);
25         int c=0,coun=1,j;
26         bool ans=1;
27         if(cow[0].x>1)
28         {
29             printf("-1\n");
30             continue;
31         }
32         int t=cow[0].y+1;
33         while(t<=T)
34         {
35             int MaxLen=t;
36             bool flag=0;
37             int k=c;
38             for(j=c+1;cow[j].x<=t&j<N;j++)
39             {
40 
41                 if(cow[j].y>=MaxLen)
42                 {
43                     k=j;
44                     MaxLen=cow[j].y;
45                     flag=1;
46                 }
47             }
48             if(flag==0)
49             {
50                 ans=0;
51                 break;
52             }
53             c=k;
54             t=MaxLen+1;
55             coun++;
56         }
57         if(ans==0)    {printf("-1\n");continue;}
58         printf("%d\n",coun);
59     }
60 }