#557831 (C++11) No.1193 Penguin Sequence

• 問題: No.1193 Penguin Sequence
• ユーザー: ianCK
• 提出日時: 2020-09-25 20:19:09
• 言語: C++11 (gcc 11.4.0)
• 結果: WA
• 実行時間: -
• コード長: 2,282 bytes
• コンパイル時間: 698 ms
• コンパイル使用メモリ: 49,024 KB
• 実行使用メモリ: 10,908 KB
• 最終ジャッジ日時: 2024-06-28 05:58:43
• 合計ジャッジ時間: 4,500 ms
• ジャッジサーバーID （参考情報）: judge5 / judge2

入力	結果	実行時間; 実行使用メモリ
testcase_00	WA	-
testcase_01	WA	-
testcase_02	WA	-
testcase_03	WA	-
testcase_04	WA	-
testcase_05	WA	-
testcase_06	WA	-
testcase_07	WA	-
testcase_08	WA	-
testcase_09	WA	-
testcase_10	WA	-
testcase_11	WA	-
testcase_12	WA	-
testcase_13	WA	-
testcase_14	WA	-
testcase_15	WA	-
testcase_16	AC	46 ms; 9,240 KB
testcase_17	AC	1 ms; 5,376 KB
testcase_18	AC	12 ms; 7,296 KB
testcase_19	WA	-
testcase_20	WA	-
testcase_21	WA	-
testcase_22	AC	14 ms; 7,424 KB
testcase_23	WA	-
testcase_24	WA	-
testcase_25	AC	22 ms; 7,936 KB
testcase_26	AC	10 ms; 7,168 KB
testcase_27	WA	-
testcase_28	WA	-
testcase_29	WA	-
testcase_30	WA	-
testcase_31	WA	-
testcase_32	WA	-
testcase_33	WA	-
testcase_34	WA	-
testcase_35	WA	-
testcase_36	WA	-
testcase_37	WA	-
testcase_38	AC	6 ms; 7,040 KB
testcase_39	AC	6 ms; 7,040 KB
testcase_40	AC	7 ms; 7,040 KB

コンパイルメッセージ

main.cpp: In function ‘int main()’:
main.cpp:63:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   63 |         scanf("%d", &n);
      |         ~~~~~^~~~~~~~~~
main.cpp:68:43: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   68 |         for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
      |                                      ~~~~~^~~~~~~~~~~~~

ソースコード

#include <stdio.h>
#include <vector>
#include <string.h>
#include <algorithm>
using namespace std;
#define PB push_back

typedef long long int ll;
constexpr int kN = int(2E5 + 10), kMod = 998244353;

struct BIT {
	int val[kN];
	void init() {memset(val, 0, sizeof(val));}
	void add(int pos) {
		while (pos < kN) {
			val[pos]++;
			pos += pos & -pos;
		}
		return ;
	}
	int ask(int pos) {
		int ans = 0;
		while (pos) {
			ans += val[pos];
			pos ^= pos & -pos;
		}
		return ans;
	}
};

ll Pow(ll a, ll b) {
	ll ans = 1;
	while (b) {
		if (b & 1) ans = ans * a % kMod;
		a = a * a % kMod;
		b >>= 1;
	}
	return ans;
}

ll Rev(ll n) {return Pow(n, kMod - 2);}

ll f[kN], inf[kN];

void pre() {
	f[0] = f[1] = inf[0] = inf[1] = 1;
	for (int i = 2; i < kN; i++) f[i] = f[i - 1] * i % kMod;
	inf[kN - 1] = Rev(f[kN - 1]);
	for (int i = kN - 1; i > 2; i--) inf[i - 1] = inf[i] * i % kMod;
	return ;
}

ll C(int n, int m) {return f[n] * inf[m] % kMod * inf[n - m] % kMod;}

int a[kN], rnk[kN]; 
ll same[kN];
BIT bit;

int main() {
	int n;
	ll ans = 0, tot = 1, tmp = 0, cnt = 0, ccnt = 0;
	vector<int> v;
	scanf("%d", &n);
	if (n == 1) {
		printf("0\n");
		return 0;
	}
	for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
	pre();
	for (int i = 1; i <= n; i++) tot = tot * C(n, i) % kMod;
	// inside
	bit.init();
	for (int i = 1; i <= n; i++) v.PB(a[i]);
	sort(v.begin(), v.end());
	v.resize(unique(v.begin(), v.end()) - v.begin());
	for (int i = 1; i <= n; i++) rnk[i] = lower_bound(v.begin(), v.end(), a[i]) - v.begin() + 1;
	for (int i = 1; i <= n; i++) {
		cnt += (i - 1) - bit.ask(rnk[i]);
		bit.add(rnk[i]);
	}
	for (int i = 2; i <= n; i++) tmp += ll(i) * (i - 1) % kMod;
	tmp %= kMod;
	ans = tmp * tot % kMod * Rev(n) % kMod * Rev(n - 1) % kMod * cnt % kMod;
	// between
	for (int i = 1; i <= n; i++) same[rnk[i]]++;
	for (int i = 1; i <= n; i++) if (same[rnk[i]]) {
		ccnt += (n - same[rnk[i]]) * same[rnk[i]] % kMod;
		same[rnk[i]] = 0;
	}
	ccnt %= kMod;
	ccnt = ccnt * Rev(2) % kMod;
	tmp = ll(n) * (n + 1) % kMod * Rev(2) % kMod;
	tmp = tmp * tmp % kMod;
	for (int i = 1; i <= n; i++) tmp -= i * i % kMod;
	tmp %= kMod;
	if (tmp < 0) tmp += kMod;
	tmp = tmp * Rev(2) % kMod;
	ans += tmp * tot % kMod * ccnt % kMod * Rev(n) % kMod * Rev(n) % kMod;

	printf("%lld\n", ans % kMod);
}