Submission #247031

#	Time	Username	Problem	Language	Result	Execution time	Memory
247031		ernestvw	Arranging Shoes (IOI19_shoes)	C++17	85 / 100	1113 ms	272736 KiB

shoes

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define sz(x) ((int)x.size())

ll subtask3(vector<int> S) {
	int n = (int)S.size();
	ll ans = 0;

	ll L = 0, R = 0;
	for(int i = 0; i < n; ++i) {
		if(S[i] > 0) {
			if(L > 0) {
				L--;
				ans += L;
			}
			else R++;
		}
		else {
			if(R > 0) {
				ans += R;
				R--;
			}
			else L++;
		}
	}

	return ans;
}

ll subtask4(vector<int> S) {
	int n = (int)S.size();
	ll ans = 0;
	for(int i = 0; i < n/2; ++i) {
		ans += (ll)i;
	}
	return ans;
}

ll subtask5(vector<int> S) {
	int n = (int)S.size();
	ll ans = 0;
	int i = 0;
	while(i < n) {
		if(S[i] < 0) {
			int j = -1;
			for(int k = i + 1; k < n; ++k) if(S[k] == -S[i]) {
				j = k;
				break;
			}
			for(int l = j; l > i + 1; --l)
				swap(S[l], S[l-1]), ++ans;
		}
		else {
			if(i > 0 && S[i-1] == -S[i]) {
				++i;
				continue;
			}
			int j = -1;
			for(int k = i + 1; k < n; ++k) if(S[k] == -S[i]) {
				j = k;
				break;
			}
			for(int l = j; l > i; --l)
				swap(S[l], S[l-1]), ++ans;			
		}
		i++;
	}
	return ans;
}

ll count_swaps(vector<int> S) {
	int n = (int)S.size();
	ll ans = 0;
	vector<bool> prise(n, false);

	bool sub3 = true;
	for(int i : S) if(abs(i) != abs(S[0])) sub3 = false;
	if(sub3) return subtask3(S);

	bool sub4 = true;
	for(int i = 0; i < n / 2; ++i)
		if(S[i] > 0 || S[i + n/2] < 0 || -S[i] != S[i + n/2])
			sub4 = false;
	if(sub4) return subtask4(S);

	//if(n <= 1000) return subtask5(S);

	vector<deque<int>> L(n+1), R(n+1);
	vector<ll> avant(n+1,0);
	for(int i = 0; i < n; ++i)
		avant[i] = n - i - 1;

	for(int i = 0; i < n; ++i) {
		int x = abs(S[i]);
		if(S[i] > 0) {
			if(sz(L[x]) > 0) {
				int j = L[x].front();
				ans += avant[j] - avant[i] - 1LL;
				for(int k = j + 1; k <= i; ++k)
					avant[k]--;
				L[x].pop_front();
			}
			else R[x].push_back(i);
		}
		else {
			if(sz(R[x]) > 0) {
				int j = R[x].front();
				ans += avant[j] - avant[i];
				for(int k = j; k <= i; ++k)
					avant[k]--;
				R[x].pop_front();
			}
			else L[x].push_back(i);
		}
	}

	return ans;
}

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