题目

思路：

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
const int maxn = 1e6 + 5, inf = 1e18, maxm = 4e4 + 5, base = 397;
const int mod = 1e9 + 7;
// const int mod = 998244353;
// const __int128 mod = 212370440130137957LL;
const int N = 1e5;
// int a[1005][1005];
int a[maxn], b[maxn];
// bool vis[maxn];
int n, m;
string s;

struct Node{
    // int val, id;
    // bool operator<(const Node &u)const{
    //     return val < u.val;
    // }
    int a, b;
    bool operator<(const Node &u)const{
        return b < u.b;
    }
}c[maxn];

void solve(){
    int res = 0;
    int k, q;
    int c;
    cin >> n >> c;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    int odd = 0, even = 0;
    res = (c + 1) * c / 2 + (c + 1);//x，y可以相同
    int sum = 0;
    for(int i = 1; i <= n; i++){
        sum += a[i] / 2 + 1;
        sum += c - a[i] + 1;
        if(a[i] % 2 == 1){
            odd++;
        }
        else{
            even++;
        }
    }
    // cout << sum << '\n';
    sum -= even * (even + 1) / 2 + odd * (odd + 1) / 2;//可以选两个相同的（a[i] <= c, 所以        
                                                      //y = (a[i] + a[j]) / 2必然小于等于c
    res -= sum;
    cout << res << '\n';
}   
    
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    int T = 1;
    cin >> T;
    while (T--)
    {
        solve();
    }
    return 0;
}