二分 例题2

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <math.h>
 4 #include <algorithm>
 5 using namespace std;
 6 const int INF=1e9+7;
 7 
 8 int N,m;
 9 int a[100005];
10 
11 bool C(int d)
12 {
13     int last=1;
14     for(int i=1;i<m;i++)
15     {
16         int crt=last+1;
17         while(crt<=N && a[crt]-a[last]<d)
18         {
19             crt++;
20         }
21         if(crt==N+1)
22             return false;
23         last=crt;
24     }
25     return true;
26 }
27 
28 int main()
29 {
30     int i,j;
31     while(scanf("%d %d",&N,&m)!=EOF)
32     {
33         for(i=1;i<=N;i++)
34             scanf("%d",&a[i]);
35         sort(a+1,a+N+1);
36         int lb=0,ub=INF;
37         while(ub-lb>1)
38         {
39             int mid=(lb+ub)/2;
40             if(C(mid))
41                 lb=mid;
42             else
43                 ub=mid;
44         }
45         printf("%d\n",lb);
46     }
47     return 0;
48 }