2016级萌新选拔赛BE题

#include<bits/stdc++.h>
using namespace std;
#define  ll long long
ll a[];
ll d[];

int main()
{
    ll n;
    ll sum=;
    cin>>n;
    for(int i=;i<n;i++)
    {
        cin>>a[i];
        sum+=a[i];
    }
    for(int i=;i<n-;i++)
    {
        d[i]=a[i+]-a[i];
    }
    d[n-]=a[]-a[n-];
    if(sum%(n*(n+)/)==)
    {
        ll k=sum/(n*(n+)/);
        for(int i=;i<n;i++)
        {
            if((k-(d[i]))%n||k-d[i]<)
            {
                cout<<"NO"<<endl;
                return ;
            }
        }
        cout<<"YES"<<endl;
    }
    else
    {
        cout<<"NO"<<endl;
    }
}

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>

using namespace std;
int a[];

int main()
{
   // freopen("in.txt","r",stdin);
  //  freopen("out.txt","w",stdout);
    int n,m,k;
    while(~scanf("%d%d%d",&n,&k,&m))
    {
        int ans=;
        for(int i=; i<(<<n); ++i)
        {
            int cnt=;
            memset(a,,sizeof(a));
            int num=i;
            while(num!=)
            {
                a[cnt++]=num%;
                num=num/;
            }
            int count=;
            num=;
            bool f=true;
            for(int j=; j<cnt; ++j)
            {
                if(a[j]==)
                {
                    if(num<m&&j!=)
                        f=false;
                    count++;
                    num=;
                }
                else
                    num++;
            }
            if(f&&count>=k)
                ans++;
        }
        printf("%d\n",ans);
    }
    return ;
}