Educational Codeforces Round 44 (Rated for Div. 2)

Educational Codeforces Round 44 (Rated for Div. 2)

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• A. Chess Placing
  

#include <bits/stdc++.h>

using namespace std;
const int MAXN=205;
int a[MAXN];


int main()
{
    int n;
    int odd=1,even=2,oddsum=0,evensum=0;
    cin>>n;
    for(int i=1;i<=(n/2);i++)
    {
        cin>>a[i];

    }
    sort(a+1,a+n/2+1);
    for(int i=1;i<=n/2;i++)
    {
        oddsum+=abs(a[i]-odd);odd+=2;
        evensum+=abs(a[i]-even);even+=2;
    }
    cout<<min(oddsum,evensum)<<endl;

    return 0;
}

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• B. Switches and Lamps
  

#include<bits/stdc++.h>

using namespace std;

const int MAXN=3000;
char c[MAXN][MAXN];
int flag[MAXN];

int main()
{
    int n,m;
    cin>>n>>m;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            cin>>c[i][j];
        }
    }
    for(int j=0;j<m;j++)
    {
        int cnt=0;
        for(int i=0;i<n;i++)
        {
            if(c[i][j]=='1')cnt++;
        }
        if(cnt==1)
        {
            for(int i=0;i<n;i++)
            {
                if(c[i][j]=='1')
                    flag[i]=1;
            }
        }
    }

    for(int i=0;i<n;i++)
        if(flag[i]==0)
    {
        cout<<"YES"<<endl;
        return 0;
    }
    cout<<"NO"<<endl;
    return 0;
}

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• C. Liebig’s Barrels
  

//二分+贪心
#include<bits/stdc++.h>

using namespace std;
#define LL long long
const LL maxn=100005;
LL a[maxn];
bool book[maxn];


int main()
{
    LL n,k,l;
    cin>>n>>k>>l;
    for(LL i=1;i<=n*k;i++)
    {
        cin>>a[i];
    }
    sort(a+1,a+n*k+1);
    //先保证n个桶差值小于l
    LL ans=0;
    if(a[n]-a[1]>l)
    {
        cout<<0<<endl;
        return 0;
    }
    else
    {
//        LL tmp;
//        for(LL i=1;i<=n*k;i++)
//        {
//            if(a[i]-a[1]>l)tmp=i-1;
//        }
//        cout<<tmp<<endl;
        LL t=upper_bound(a+1,a+n*k+1,l+a[1])-a;
        //cout<<t<<" "<<a[t]<<endl;
        t=t-1;
        LL flag=0;
        for(LL i=1;i<=t;i+=k)
        {
            ans+=a[i];flag++;
            book[i]=true;
            if(flag==n)break;
        }
        for(LL j=t;j>=1;j--)
        {
            if(flag==n)break;
            if(!book[j])
            {
                ans+=a[j];
                flag++;
            }
            if(flag==1)break;
        }
        cout<<ans<<endl;
    }
    return 0;

}