Submission #225877

#	Time	Username	Problem	Language	Result	Execution time	Memory
225877		staniewzki	Sorting (IOI15_sorting)	C++17	100 / 100	442 ms	11492 KiB

sorting

#include<bits/stdc++.h>
using namespace std;
 
#define REP(i, n) for(int i = 0; i < n; i++)
 
#include "sorting.h"

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	auto check = [&](int R) {
		vector<int> s(N), ws(N), wf(N);
		REP(i, N) s[i] = S[i];
		auto f = s;
		REP(i, R) swap(f[X[i]], f[Y[i]]);
		REP(i, N) {
			ws[S[i]] = i;
			wf[f[i]] = i;
		}

		int j = 0;
		REP(i, R) {
			int &p = s[X[i]], &q = s[Y[i]];
			swap(p, q);
			swap(ws[p], ws[q]);

			while(j < N && j == f[j]) j++;
			if(j < N) {
				int &a = ws[j], &b = ws[f[j]], &x = wf[j], &y = wf[f[j]];
				P[i] = a, Q[i] = b;
				swap(a, b), swap(s[a], s[b]);
				swap(x, y), swap(f[x], f[y]);
			}
			else P[i] = Q[i] = 0;
		}
		REP(i, N) if(i != s[i]) return false;
		return true;
	};

	int l = 0, r = M;
	while(l < r) {
		int m = (l + r) / 2;
		if(check(m))
			r = m;
		else
			l = m + 1;
	}

	check(l);
	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