Codeforces Round #574 (Div. 2)

Codeforces Round #574 (Div. 2)

A

# include <bits/stdc++.h>
using namespace std;
​
const int MAXN=1e3+100;
int a[MAXN];
int main()
{
    int n,k;
    int sum=0;
    scanf("%d %d",&n,&k);
    for(int i=1;i<=n;i++){
        int aa;
        scanf("%d",&aa);
        a[aa]++;
    }
    
    int b;
    if(n%2==0) b=n/2;
    else b=n/2+1;
    
    int c;
    for(int i=1;i<=k;i++){
        if(a[i]!=1){
            c=a[i]/2;
            if(c<=b){
                sum+=c*2;
                a[i]=a[i]/2*2;
                b=b-c;
            }else{
                sum+=b*2;
                a[i]=a[i]-b*2;
                b=0;
                break;
            }   
        }
    }
    
    //cout<<"@@@"<<sum<<endl;
    if(b){
        for(int i=1;i<=k;i++){
            if(b){
                if(a[i]){
                    sum+=1;
                    a[i]=0;
                    b--;
                }
            }
        }
    }
    
    printf("%d",sum);
    return 0;
}
​

B

# include <bits/stdc++.h>
using namespace std;
​
typedef long long LL;
int main()
{
    LL n,k;
    scanf("%lld %lld",&n,&k);
    
    LL sum=0;
    sum=(sqrt(9+8*(n+k))-3)/2;
    
    printf("%lld",n-sum);
    return 0;
}
​

C

# include <bits/stdc++.h>
using namespace std;
​
const int MAXN=1e5+100;
typedef long long LL;
LL h1[MAXN];
LL h2[MAXN];
LL f[MAXN][3];
int main()
{
    int n;
    scanf("%d",&n);
    
    for(int i=1;i<=n;i++){
        scanf("%lld",&h1[i]); 
    }
    
    for(int i=1;i<=n;i++){
        scanf("%lld",&h2[i]);
    }
    
    for(int i=1;i<=n;i++){
        
        f[i][1]=max(f[i-1][0],f[i-1][2])+h1[i];
        f[i][2]=max(f[i-1][0],f[i-1][1])+h2[i];
        f[i][0]=max(max(f[i-1][0],f[i-1][1]),f[i-1][2]);
    }
    
    cout<<max(max(f[n][0],f[n][1]),f[n][2]);
    return 0;
}
​

D

# include <bits/stdc++.h>
using namespace std;
​
const int MAXN=1e5+100;
typedef long long LL;
LL a[MAXN];
LL mod=998244353;
int main()
{
    int n;
    LL ans=0;
    LL sum=0;
    scanf("%d",&n);
    
    for(int i=1;i<=n;i++){
        scanf("%lld",&a[i]);
        int b=11;
        while(a[i]){
            ans=(ans+(b*(a[i]%10))%mod)%mod;
            b=((b%mod)*100)%mod;
            a[i]=a[i]/10;
            //cout<<b<<endl;
            //cout<<"@@@"<<ans<<endl;
        }
        //cout<<ans<<endl;
        sum=(sum%mod+ans)%mod;
        ans=0;
    }/*
    for(int i=1;i<=n;i++){
        LL t=11;
        while(a[i]>0) ans=(1ll*a[i]%10*t)%mod,t=t*100%mod,a[i]=a[i]/10;
        cout<<ans<<endl;
    }*/
    sum=(n*sum)%mod;
    
    printf("%lld",sum);
    return 0;
}
​