hdu 4004 The Frog's Games

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<cmath>
 6 #include<algorithm>
 7 #define inf 0x7fffffff
 8 using namespace std;
 9 const int maxn=500000+100;
10 int an[maxn];
11 int L,n,m;
12 int isok(int len)
13 {
14     int step=0;
15     int from=0;
16     int i=1;
17     while (from<L && i<=n+1)
18     {
19         int j=i;
20         while (an[i]-from<=len && i<=n+1) {j=i ;i++ ; }
21         step ++ ;
22         from=an[j];
23         i=j;
24         if (step>m) return 0;
25     }
26     return 1;
27 }
28 int main()
29 {
30     while (scanf("%d%d%d",&L,&n,&m)!=EOF)
31     {
32         for (int i=1 ;i<=n ;i++) scanf("%d",&an[i]);
33         an[n+1]=L;
34         sort(an+1,an+n+1+1);
35         int l=0,r=inf;
36         int ans=0;
37         while (l<=r)
38         {
39             int mid=(l+r)>>1;
40             if (isok(mid)) {ans=mid ;r=mid-1 ; }
41             else l=mid+1 ;
42         }
43         printf("%d\n",ans);
44     }
45     return 0;
46 }