【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

 #include<algorithm>
 #include<iostream>
 #include<cstdlib>
 #include<cstring>
 #include<cstdio>
 #include<cmath>
 #include<queue>
 using namespace std;

 typedef long long LL;

 #define INF 1LL<<60
 #define N 100010

 int n,k;
 LL l,r,L,R;

 LL a[N];

 LL work(LL x)
 {
     LL res(),cnt();
     for (int i=;i<=n;i++)
     {
         res=max(res+a[i],0LL);
         if (res>=x)

             res=,cnt++;
     }
     return cnt;
 }

 int main()
 {
     scanf("%d%d",&n,&k);
     for (int i=;i<=n;i++)
         scanf("%lld",&a[i]);
     l=;
     r=INF;
     while (l<=r)
     {
         LL m=(l+r)>>;
         if (work(m)>k)
             L=m,l=m+;
         else
             r=m-;
     }
     l=;
     r=INF;
     while (l<=r)
     {
         LL m=(l+r)>>;
         if (work(m)<k)
             R=m,r=m-;
         else
             l=m+;
     }
     L++;
     R--;
     if (work(L)!=k || work(R)!=k)
         printf("-1\n");
     else
         printf("%lld %lld",L,R);
     return ;
 }