Submission #764851

#	Time	Username	Problem	Language	Result	Execution time	Memory
764851		SanguineChameleon	Sorting (IOI15_sorting)	C++17	36 / 100	49 ms	848 KiB

sorting

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

const int maxN = 2e5 + 20;
int cnt[maxN];

mt19937 gen(69420);

bool cmp(int i, int j) {
	return cnt[i] < cnt[j];
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	for (int i = 0; i < M; i++) {
		cnt[X[i]]++;
		cnt[Y[i]]++;
	}
	int len = 0;
	for (int i = 0; ; i++) {
		bool ok = true;
		for (int j = 0; j < N; j++) {
			if (S[j] != j) {
				ok = false;
				break;
			}
		}
		if (ok) {
			return len;
		}
		assert(i < M);
		cnt[X[i]]--;
		cnt[Y[i]]--;
		swap(S[X[i]], S[Y[i]]);
		vector<int> wrong;
		for (int j = 0; j < N; j++) {
			if (S[j] != j) {
				wrong.push_back(j);
			}
		}
		if (wrong.empty()) {
			P[len] = 0;
			Q[len] = 0;
		}
		else {
			if ((int)wrong.size() >= 10) {
				sort(wrong.begin(), wrong.end(), cmp);
				shuffle(wrong.begin(), wrong.begin() + 10, gen);
			}
			else {
				shuffle(wrong.begin(), wrong.end(), gen);
			}
			P[len] = wrong[0];
			for (int j = 0; j < N; j++) {
				if (S[j] == wrong[0]) {
					Q[len] = j;
					break;
				}
			}
		}
		swap(S[P[len]], S[Q[len]]);
		len++;
	}
}

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 16 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26