結果

問題 No.742 にゃんにゃんにゃん 猫の挨拶
ユーザー tkmst201tkmst201
提出日時 2021-02-25 11:59:26
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 12 ms / 2,500 ms
コード長 2,911 bytes
コンパイル時間 1,900 ms
コンパイル使用メモリ 204,388 KB
最終ジャッジ日時 2025-01-19 04:26:39
ジャッジサーバーID
(参考情報)
judge3 / judge5
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ファイルパターン 結果
other AC * 16
権限があれば一括ダウンロードができます
コンパイルメッセージ
main.cpp: In function ‘int main()’:
main.cpp:74:24: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   74 |         REP(i, N) scanf("%d", &M[i]), --M[i];
      |                   ~~~~~^~~~~~~~~~~~~

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//
/**
* @brief https://tkmst201.github.io/Library/DataStructure/BinaryIndexedTree.hpp
*/
template<typename T>
struct BinaryIndexedTree {
using value_type = T;
using const_reference = const value_type &;
using F = std::function<value_type (const_reference, const_reference)>;
using size_type = std::size_t;
private:
size_type n;
F f;
value_type id_elem;
std::vector<value_type> node;
public:
BinaryIndexedTree(size_type n, const F & f, const_reference id_elem)
: n(n), f(f), id_elem(id_elem), node(n + 1, id_elem) {}
size_type size() const noexcept {
return n;
}
void add(size_type i, const_reference x) {
assert(i < size());
++i;
for (; i <= size(); i += i & -i) node[i] = f(node[i], x);
}
value_type sum(size_type i) const {
assert(i <= size());
value_type res = id_elem;
for (; i > 0; i -= i & -i) res = f(node[i], res);
return res;
}
size_type lower_bound(const_reference x) const {
size_type res = 0;
size_type s = id_elem, w = 1;
while (w < size()) w <<= 1;
for (; w > 0; w >>= 1) {
if (res + w <= size()) {
value_type cur = f(s, node[res + w]);
if (cur < x) {
res += w;
s = cur;
}
}
}
return res;
}
};
int main() {
int N;
cin >> N;
vector<int> M(N);
REP(i, N) scanf("%d", &M[i]), --M[i];
ll ans = 0, ansiso = 0;
REP(t, 2) {
// -> count
vector<int> isosum(N + 1);
REP(i, N) {
if (i == M[i]) ++isosum[i + 1];
isosum[i + 1] += isosum[i];
}
BinaryIndexedTree<int> bit(N, [](int x, int y) { return x + y; }, 0);
vector<int> evf(N), ev(N); // cnt, sum
REP(i, N) {
if (evf[i]) ans += bit.sum(i) - ev[i];
if (i < M[i]) {
const int cur = bit.sum(M[i]);
ans += bit.sum(N) - cur;
bit.add(M[i], 1);
evf[M[i]] = true;
ev[M[i]] = cur;
ansiso += isosum[M[i] + 1] - isosum[i];
}
}
vector<int> mp(N);
REP(i, N) mp[M[i]] = i;
bit = BinaryIndexedTree<int>(N, [](int x, int y) { return x + y; }, 0);
vector<int> sum(N + 1);
FOR(i, 1, N + 1) sum[i] = sum[i - 1] + (M[i - 1] < i - 1);
for (int i = N - 1; i >= 0; --i) {
if (M[i] < i) bit.add(M[i], 1);
if (mp[i] < i) {
ans += bit.sum(i + 1);
ans += sum[i] - sum[mp[i]];
}
}
REP(i, N) M[i] = N - 1 - M[i];
reverse(ALL(M));
}
ans = ans / 2 + ansiso;
cout << ans << endl;
}
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