B. Contest Preparation

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <map>
#define inf 0x3f3f3f3f
#define endl '\n'
#define int long long

using namespace std;

const int N = 1e5 + 10, mod = 1e6;
//typedef long long ll;
typedef pair<int,int> PII;
//queue<PII> q1;
//priority_queue <int,vector<int>,greater<int> > q2;
int n,m,t,k;
int ans;
/*
*/
void solve()
{
    cin >> n >> m;
    if( !n ){
        cout << 0 << endl;
        return;
    }
    if(n > 0 && n <= m){
        cout << 2 << endl;
        return ;
    }
    cout << (n * 2 + m - 1) / m << endl;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int Ke_scholar  = 1;
    cin >> Ke_scholar;
    //cin.ignore();
    while(Ke_scholar--)
        solve();
    return 0;
}

K. Triangles

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <map>
#define inf 0x3f3f3f3f
#define endl '\n'
#define int long long

using namespace std;

const int N = 510, mod = 1e6;
//typedef long long ll;
typedef pair<int,int> PII;
//queue<PII> q1;
//priority_queue <int,vector<int>,greater<int> > q2;
int n,m,t,k;
int ans;
int f[N][N];
/*
*/
void solve()
{
    cin >> n;
    for(int i = 0;i < n;i ++){
        int x,y;
        cin >> x >> y;
        f[x][y] = 1;
    }
    for(int i = 0;i < N;i++){
        for(int j = 0; j < N;j++){
            if(f[i][j])
                f[i][j] += f[i - 1][j - 1];
        }
    }
    int ans = 0;
    for(int i = 0;i < N;i ++)
        for(int j = 0;j < N;j ++)
            ans += f[i][j];
    cout << ans * 2 << endl;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int Ke_scholar  = 1;
    //cin >> Ke_scholar;
    //cin.ignore();
    while(Ke_scholar--)
        solve();
    return 0;
}

M. XOR Almost Everything

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <set>
#include <map>
#define inf 0x3f3f3f3f
#define endl '\n'
#define int long long

using namespace std;

const int N = 1e5 + 10, mod = 1e6;
//typedef long long ll;
typedef pair<int,int> PII;
//queue<PII> q1;
//priority_queue <int,vector<int>,greater<int> > q2;
int n,m,t,k;
int ans,a[N];
/*
*/
void solve()
{
    cin >> n;
    for(int i = 1;i <= n; i++){
        cin >> a[i];
        ans ^= a[i];
    }
    if(ans == 0 || n % 2 == 0)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int Ke_scholar  = 1;
    //cin >> Ke_scholar;
    //cin.ignore();
    while(Ke_scholar--)
        solve();
    return 0;
}