JZYZOJ1452 NOIP2015_提高组Day2_1_跳石头

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 #include<cmath>
 5 #include<iostream>
 6 using namespace std;
 7 const int maxn=100010;
 8 int z,m,n;
 9 int a[maxn]={},tot=0;
10 int check(int x){
11     int y=0;int w=0,hug=z,t1=z;
12     for(int i=1;i<=n+1;i++){
13         if(a[i]-a[y]>=x){
14             hug=min(hug,t1);
15             t1=a[i]-a[y];
16             w+=(i-y-1);y=i;
17         }
18     }if(n+1!=y){
19         w+=n+1-y;
20         if(y==0)w--;
21         t1+=a[n+1]-a[y];
22         hug=min(hug,t1);
23     }
24     if(w==m){
25         if(hug<x) return 0;
26         else return 1;
27     }
28     else if(w>m) return 0;
29     else return 1;
30 }
31 int doit(){
32     int l=0,r=z;
33     while(l+1<r){
34         int mid=(l+r)/2;
35         int w=check(mid);
36         if(!w)r=mid-1;
37         else l=mid;
38     }int w=check(r);
39     if(!w)return l;
40     else return r;
41 }
42 int main(){
43     //freopen("wtf.in","r",stdin);
44     scanf("%d%d%d",&z,&n,&m);
45     tot=n+1;
46     for(int i=1;i<=n;i++){
47         scanf("%d",&a[i]);
48     }a[n+1]=z;
49     printf("%d\n",doit());
50     return 0;
51 }