Submission #599277

#	Time	Username	Problem	Language	Result	Execution time	Memory
599277		Temmie	Sorting (IOI15_sorting)	C++17	100 / 100	220 ms	19212 KiB

sorting

#include <bits/stdc++.h>

int findSwapPairs(int n, int s[], int m, int u[], int v[], int uu[], int vv[]) {
	std::vector <int> a(s, s + n);
	std::vector <int> o(s, s + n);
	int l = 0, r = m;
	std::vector <std::pair <int, int>> last;
	while (l < r) {
		int mid = (l + r) >> 1;
		a = o;
		std::vector <bool> vis(n, false);
		std::vector <std::pair <int, int>> now;
		for (int i = 0; i < mid; i++) {
			std::swap(a[u[i]], a[v[i]]);
		}
		auto f = [&] (auto&& self, int ind, int root) -> void {
			vis[ind] = true;
			now.emplace_back(ind, a[ind]);
			if (a[ind] != root) {
				self(self, a[ind], root);
			}
		};
		for (int i = 0; i < n; i++) {
			if (!vis[i] && a[i] != i) {
				f(f, a[i], i);
			}
		}
		if ((int) now.size() > mid) {
			l = mid + 1;
		} else {
			r = mid;
		}
	}
	a = o;
	std::vector <bool> vis(n, false);
	auto f = [&] (auto&& self, int ind, int root) -> void {
		vis[ind] = true;
		last.emplace_back(ind, a[ind]);
		if (a[ind] != root) {
			self(self, a[ind], root);
		}
	};
	for (int i = 0; i < l; i++) {
		std::swap(a[u[i]], a[v[i]]);
	}
	for (int i = 0; i < n; i++) {
		if (!vis[i] && a[i] != i) {
			f(f, a[i], i);
		}
	}
	a = o;
	std::vector <int> inv(n);
	for (int i  = 0; i < n; i++) {
		inv[a[i]] = i;
	}
	for (int i = 0; i < l; i++) {
		std::swap(a[u[i]], a[v[i]]);
		std::swap(inv[a[u[i]]], inv[a[v[i]]]);
		if (i < (int) last.size()) {
			uu[i] = inv[last[i].first];
			vv[i] = inv[last[i].second];
			std::swap(a[uu[i]], a[vv[i]]);
			std::swap(inv[a[uu[i]]], inv[a[vv[i]]]);
		} else {
			uu[i] = vv[i] = 0;
		}
	}
	return l;
}

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 16 / 16
• Subtask 4: 18 / 18
• Subtask 5: 20 / 20
• Subtask 6: 26 / 26