HDU 4190 Distributing Ballot Boxes【二分答案】

 1 #include<iostream>  
 2 #include<cstdio>  
 3 #include<cstring> 
 4 #include <cmath> 
 5 #include<stack>
 6 #include<vector>
 7 #include<map> 
 8 #include<set>
 9 #include<queue> 
10 #include<algorithm>  
11 using namespace std;
12 
13 typedef long long LL;
14 const int INF = (1<<30)-1;
15 const int mod=1000000007;
16 const int maxn=1000005;
17 
18 int a[maxn];
19 int n,m;
20 
21 int ok(int x){
22     int ans=0;
23     for(int i=1;i<=n;i++){
24         int tmp=a[i]/x;
25         if(a[i]%x) tmp++;
26         ans+=tmp;
27     }
28     if(ans<=m) return 1;
29     return 0;
30 }
31 
32 int main(){
33     while(scanf("%d %d",&n,&m)!=EOF){
34         if(n==-1&&m==-1) break;
35         
36         int maxx=-INF;
37         for(int i=1;i<=n;i++) {
38             scanf("%d",&a[i]);
39             maxx=max( a[i] , maxx );
40         }
41         
42         int l=0,r=maxx,mid;
43         while(l<r){
44             mid=(l+r)/2;    
45             if(ok(mid)) r=mid;
46             else l=mid+1;
47         }
48         printf("%d\n",l);
49     }
50     return 0;
51 }