Problem - B - Codeforces

题意：

思路：

直接枚举是去掉哪个店，然后计算贡献即可

虽然赛时做出来了，但是这种计算还是感觉不熟练

 

Code：

#include <bits/stdc++.h>

#define int long long

using i64 = long long;

constexpr int N = 2e5 + 10;
constexpr int mod = 998244353;

int n, m, d;
int a[N];

int calc(int l, int r) {
    return (a[r] - a[l]) / d + ((a[r] - a[l]) % d != 0);
}
void solve() {
    std::cin >> n >> m >> d;

    for (int i = 1; i <= m; i ++) {
        std::cin >> a[i];
    }

    a[0] = 1;
    a[m + 1] = n + 1;

    int sum = 0;
    int st = 0;
    if (a[1] == 1) st = 1;
    for (int i = st; i <= m; i ++) {
        sum += calc(i, i + 1);
    }

    int res = sum;
    std::vector<int> ans;
    int mi = 1e9;
    for (int i = 1; i <= m; i ++) {
        res = sum;
        res += calc(i - 1, i + 1) - (calc(i - 1, i) + calc(i, i + 1));
        mi = std::min(mi, res);
    }

    int cnt = 0;
    for (int i = 1; i <= m; i ++) {
        res = sum;
        res += calc(i - 1, i + 1) - (calc(i - 1, i) + calc(i, i + 1));
        if (mi == res) cnt ++;
    }

    std::cout << mi << " " << cnt << "\n";

}
signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int t = 1;
	std::cin >> t;

    while (t--) {
        solve();
    }
    
    return 0;
}