2020牛客暑期多校训练营（第六场）

B Binary Vector

费马小定理(快速幂+逆元)

#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define T int t ;cin >> t;while(t--)
using namespace std ;
typedef long long ll;
const ll mod = 1e9 + 7;
long long quickpow(long long a,long long b)
{
    if(b<0)  return 0;
    long long ret=1;
    a%=mod;
    while(b)
    {
        if(b & 1 ) ret = ( ret *a ) % mod;
                             b>>=1;
        a = (a * a)% mod;
    }
    return ret;
}
long long inv(long long a)
{
    return quickpow(a,mod-2);
}
ll s[200000010];
void solve()
{
    ll inv2=inv(2);
    ll i;
    ll niyuan=inv2;
    ll sum=0,res=1;
    for(i=1;i<20000002;i++)
    {
        res=res*(1-niyuan+mod)%mod;
        niyuan=niyuan*inv2%mod;
        sum^=res;
        s[i]=sum;
    }

}
int main()
{
    solve();
    T
    {
        int n;
        scanf("%d",&n);
        printf("%lld
",s[n]);
    }
}

C Combination of Physics and Maths

#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
double a[205][205];
double b[205];
int main()
{
    ll t;
    scanf("%lld",&t);
    while(t--)
    {
        memset(b, 0, sizeof b);
        ll n,m;
        ll i,j;
        double mm=0;
        scanf("%lld%lld",&n,&m);
        for(i=0; i<n; i++)
        {
            for(j=0; j<m; j++)
            {
                scanf("%lf",&a[i][j]);
                b[j]+=a[i][j];
                mm=max(mm,b[j]/a[i][j]);
            }

        }
        printf("%.8lf
",mm);
    }
}

E Easy Construction

1

#include<cstdio>
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
    int n,k;
    scanf("%d%d",&n,&k);
    {
        if(k==0)
        {
            printf("-1");
        }
        else
        {
            if((n*(n+1)/2)%n==k)
            {
                for(int i=1; i<=n; i++)
                {
                    if(i!=1)
                    {
                        printf(" ");
                    }
                    printf("%d",i);
                }
                printf("
");
            }
            else
            {
                printf("-1
");
            }
        }
    }
}