CodeForces Round #563 Div.2

A. Ehab Fails to Be Thanos

#include <bits/stdc++.h>
using namespace std;
 
const int maxn = 1e5 + 10;
int N;
int a[maxn];
 
int main() {
   scanf("%d", &N);
    for(int i = 0; i < N * 2; i ++)
        scanf("%d", &a[i]);
    
    sort(a, a + N * 2);
    
    long long sum1 = 0, sum2 = 0;
    for(int i = 0; i < N; i ++)
        sum1 += a[i];
    for(int i = N; i < N * 2; i ++)
        sum2 += a[i];
    
    if(sum1 != sum2) {
        for(int  i = 0; i < N * 2; i ++)
            printf("%d%s", a[i], i != 2 * N - 1 ? " " : "
");
    } else printf("-1
");
    
    
    return 0;
}

B. Ehab Is an Odd Person

#include <bits/stdc++.h>
using namespace std;
 
const int maxn = 1e5 + 10;
int N;
int odd = 0, even = 0;
long long a[maxn];
 
int main() {
    scanf("%d", &N);
    for(int i = 0; i < N; i ++) {
        scanf("%lld", &a[i]);
        if(a[i] % 2 == 0) even ++;
        else odd ++;
    }
    if(odd && even) sort(a, a + N);
    
    for(int i = 0; i < N; i ++)
        printf("%lld%s", a[i], i != N - 1 ? " " : "
");
    
    return 0;
}

C. Ehab and a Special Coloring Problem

#include <bits/stdc++.h>
using namespace std;
 
const int maxn = 1e5 + 10;
int N;
int pos[maxn];
 
bool isprime(int x) {
    if(x <= 1) return false;
    if(x == 2) return true;
    
    for(int i = 2; i * i <= x; i ++) {
        if(x % i == 0) return false;
    }
    
    return true;
    
}
 
void solve() {
    int p = 1;
    
    for(int i = 2; i <= N; i ++) {
        if(isprime(i)) {
            pos[i] = p;
            for(int j = i; j < maxn; j += i)
                pos[j] = p;
            
            p ++;
            
        }
    }
    
}
 
int main() {
    scanf("%d", &N);
    solve();
    
    for(int i = 2; i <= N; i ++) 
        printf("%d%s", pos[i], i != N ? " " : "
");
    
    return 0;
} 

D. Ehab and the Expected XOR Problem

#include <bits/stdc++.h>
using namespace std;
 
const int maxn = (1 << 18) + 10;
int N, x;
int vis[maxn];
vector<int> ans;
 
int main() {
    scanf("%d%d", &N, &x);    
    
    for(int i = 0; i < 1 << N; i ++) {
        if(!vis[i]) vis[i ^ x] = 1;
    }
    
    int t = 0;
    for(int i = 1; i < 1 << N; i ++) {
        if(!vis[i]) {
            ans.push_back(t ^ i);
            t = i;
        }
    }
    
    printf("%d
", (int)ans.size());
    for(int i = 0; i < (int)ans.size(); i ++)
        printf("%d%s", ans[i], i != (int)ans.size() - 1 ? " " : "
");
    
    return 0;
}

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