洛谷 1316 丢瓶盖

【题解】

　　二分答案+贪心check.

 1 #include<cstdio>
 2 #include<algorithm>
 3 #include<cstring>
 4 #define LL long long
 5 #define rg register
 6 #define N 200010
 7 using namespace std;
 8 int n,m,a[N],l,r,mid;
 9 inline int read(){
10     int k=0,f=1; char c=getchar();
11     while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar();
12     while('0'<=c&&c<='9')k=k*10+c-'0',c=getchar();
13     return k*f;
14 }
15 inline bool check(){
16     int sum=1,last=a[1];
17     for(rg int i=2;i<=n;i++)if(a[i]-last>=mid){
18         sum++;
19         last=a[i];
20     }
21 //    printf("mid=%d sum=%d\n",mid,sum);
22     return sum>=m;
23 }
24 int main(){
25     n=read(); m=read();
26     for(rg int i=1;i<=n;i++) a[i]=read();
27     sort(a+1,a+1+n);
28     l=0; r=a[n]-a[1]+1;
29     while(l+1<r){
30         mid=(l+r)>>1;
31         if(check()) l=mid; else r=mid;
32     }
33     printf("%d\n",l);
34     return 0;
35 }
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posted @ 2018-07-31 20:15  Driver_Lao  阅读(178)  评论(0)  编辑  收藏  举报