【bzoj4590】[Shoi2015]自动刷题机

因为解一定是单调的，n越小切的题越多，这是可以肯定的，那么直接二分答案

 1 #include<algorithm>
 2 #include<iostream>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<cmath>
 7 #include<queue>
 8 using namespace std;
 9  
10 typedef long long LL;
11  
12 #define INF 1LL<<60
13 #define N 100010
14  
15 int n,k;
16 LL l,r,L,R;
17  
18 LL a[N];
19  
20 LL work(LL x)
21 {
22     LL res(0),cnt(0);
23     for (int i=1;i<=n;i++)
24     {
25         res=max(res+a[i],0LL);
26         if (res>=x)
27  
28             res=0,cnt++;
29     }
30     return cnt;
31 }
32  
33 int main()
34 {
35     scanf("%d%d",&n,&k);
36     for (int i=1;i<=n;i++)
37         scanf("%lld",&a[i]);
38     l=1;
39     r=INF;
40     while (l<=r)
41     {
42         LL m=(l+r)>>1;
43         if (work(m)>k)
44             L=m,l=m+1;
45         else
46             r=m-1;
47     }
48     l=1;
49     r=INF;
50     while (l<=r)
51     {
52         LL m=(l+r)>>1;
53         if (work(m)<k)
54             R=m,r=m-1;
55         else
56             l=m+1;
57     }
58     L++;
59     R--;
60     if (work(L)!=k || work(R)!=k)
61         printf("-1\n");
62     else
63         printf("%lld %lld",L,R);
64     return 0;
65 }

 

 
posted @ 2016-05-17 16:31  Yangjiyuan  阅读(433)  评论(0)  编辑  收藏  举报