提出 #69709559

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ソースコード 拡げる

#include<bits/stdc++.h>
#define L(i, j, k) for(int i = (j); i <= (k); i++)
#define R(i, j, k) for(int i = (j); i >= (k); i--)
#define ll long long
#define sz(a) ((int) a.size())
#define vi vector<int>
#define pb emplace_back
#define me(a, x) memset(a, x, sizeof(a))
using namespace std;
const int N = 1e6 + 7, mod = 998244353, inv2 = (mod + 1) / 2;
int qpow(int x, int y = mod - 2) {
	int res = 1;
	for(; y; x = (ll) x * x % mod, y >>= 1) if(y & 1) res = (ll) res * x % mod;
	return res;
}
int fac[N], ifac[N], inv[N];
void init(int x) {
	fac[0] = ifac[0] = inv[1] = 1;
	L(i, 2, x) inv[i] = (ll) (mod - mod / i) * inv[mod % i] % mod;
	L(i, 1, x) fac[i] = (ll) fac[i - 1] * i % mod, ifac[i] = (ll) ifac[i - 1] * inv[i] % mod;
} 
int C(int x, int y) {
	return x < y || y < 0 ? 0 : (ll) fac[x] * ifac[y] % mod * ifac[x - y] % mod;
}
inline int sgn(int x) {
	return (x & 1) ? mod - 1 : 1;
}
int n, k, m;
int a[N];
int ans;
int main() {
	ios :: sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	cin >> m >> k >> n;
	L(i, 1, n) {
		cin >> a[i];
		a[i + n] = a[i] + m;
	}
	ans = n * 4;
	L(l, 1, n) {
		int p = lower_bound(a + l, a + l + n, a[l] + k) - a - l;
		if(p >= 3) {
			(ans += p - 2) %= mod;
		}
	}
	ans = (ll)ans * qpow(2, n - 1) % mod * inv2 % mod * inv2 % mod;
	cout << ans << '\n';
	return 0;
}

提出情報

ジャッジ結果