Codeforces 526E Transmitting Levels

http://codeforces.com/contest/526/problem/E

题意:给一个环，每个点有权值，每次给一个数B,求把这个环切割成若干部分，每个部分不超过B，至少要切成几块？

#include<cstdio>
#include<cmath>
#include<iostream>
#include<cstring>
#include<algorithm>
#define ll long long
ll a[2000005];
int g[2000005],f[2000005];
int n,m;
ll read(){
    ll t=0,f=1;char ch=getchar();
    while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}
    while ('0'<=ch&&ch<='9'){t=t*10+ch-'0';ch=getchar();}
    return t*f;
}
int main(){
    n=read();m=read();
    for (int i=1;i<=n;i++)
     a[i]=read(),a[i+n]=a[i];
    for (int i=1;i<=2*n;i++)
     a[i]+=a[i-1];
    while (m--){
        for (int i=1;i<=2*n;i++)
         g[i]=i,f[i]=0;
        ll T=read();
        int j=1,ans=0x7fffffff;
        for (int i=n+1;i<=2*n;i++){
            while (j<=i&&a[i]-a[j-1]>T) j++;
            f[i]=f[j-1]+1;
            g[i]=g[j-1];
            if (i-g[i]>=n) ans=std::min(ans,f[i]);
        } 
        printf("%d
",ans);
    } 
    return 0;
}