Submission #1278604

#	Time	Username	Problem	Language	Result	Execution time	Memory
1278604		IBory	Arranging Shoes (IOI19_shoes)	C++20	0 / 100	1 ms	336 KiB

shoes

#include "shoes.h"
#include <bits/stdc++.h>
#define pii pair<int, int>
typedef long long ll;
using namespace std;

const int MAX = 200007;

struct BIT {
	int T[MAX];
	void Update(int i, int v) {
		for (i += 3; i < MAX; i += i & -i) T[i] += v;
	}
	int Query(int L, int R) {
		int ret = 0; L--;
		for (L += 3; R; R -= R & -R) ret += T[R];
		for (R += 3; L; L -= L & -L) ret -= T[L];
		return ret;
	}
} T;

ll count_swaps(vector<int> S) {
	int N = S.size();
	map<int, vector<int>> C;
	for (int i = 0; i < N; ++i) C[S[i]].push_back(i);
	for (auto& [_, v] : C) reverse(v.begin(), v.end());

	ll ret = 0;
	vector<pii> P;
	for (int i = 0; i < N; ++i) {
		if (C[S[i]].empty() || C[S[i]].back() != i) continue;
		int t = C[-S[i]].back(); C[-S[i]].pop_back();
		P.emplace_back(i, t);
		if (0 < S[i]) ret++;
	}

	for (auto [a, b] : P) {
		ret += (b - a) - T.Query(a, b);
		T.Update(b, 1);
	}

	return ret;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 15