COGS2642 / Bzoj4590 [Shoi2015]自动刷题机

 1 /*by SilverN*/
 2 #include<algorithm>
 3 #include<iostream>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<cmath>
 7 #include<vector>
 8 #define LL long long
 9 using namespace std;
10 const LL INF=1ll<<61;
11 const int mxn=100010;
12 int read(){
13     int x=0,f=1;char ch=getchar();
14     while(ch<‘0‘ || ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
15     while(ch>=‘0‘ && ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
16     return x*f;
17 }
18 int L,m,a[mxn];
19 LL ansmi,ansmx;
20 LL solve(LL lim){
21     LL tmp=0;
22     LL sv=0;
23     for(int i=1;i<=L;i++){
24         tmp+=a[i];
25         if(tmp<0)tmp=0;
26         if(tmp>=lim){
27             ++sv;
28             tmp=0;
29         }
30     }
31     return sv;
32 }
33 int main(){
34     int i,j;
35     L=read();m=read();
36     for(i=1;i<=L;i++)
37         a[i]=read();
38     LL l=1,r=INF;
39     while(l<=r){
40         LL mid=(l+r)>>1;
41         if(solve(mid)>=m){
42             ansmx=mid;
43             l=mid+1;
44         }
45         else r=mid-1;
46     }
47     l=1;r=ansmx;
48     while(l<=r){
49         LL mid=(l+r)>>1;
50         if(solve(mid)<=m){
51             ansmi=mid;
52             r=mid-1;
53         }
54         else l=mid+1;
55     }
56     if(solve(ansmx)==m)printf("%lld %lld\n",ansmi,ansmx);
57     else printf("-1\n");
58     return 0;
59 }