Submission #785473

#	Time	Username	Problem	Language	Result	Execution time	Memory
785473		Sohsoh84	Sorting (IOI15_sorting)	C++17	100 / 100	205 ms	21500 KiB

sorting

#include "sorting.h"
#include <bits/stdc++.h>

using namespace std;

#define debug(x)		cerr << #x << ": " << x << endl;
#define sep			' '

const int MAXN = 1e6 + 10;

int X[MAXN], Y[MAXN], n, m, ans_A[MAXN], ans_B[MAXN], T[MAXN], P[MAXN], S[MAXN], ind[MAXN];

inline void check(set<int>& st, int x) {
	if (st.find(x) != st.end()) st.erase(x);
	if (P[x] != x) st.insert(x);
}

inline bool solve(int m) {
	// P: jaye mellat too jaygasht nahayii baad swap ha
	for (int i = 0; i < n; i++) T[i] = S[i];
	for (int i = 0; i <= m; i++) swap(T[X[i]], T[Y[i]]);
	for (int i = 0; i < n; i++) P[T[i]] = i;

	for (int i = 0; i < n; i++) { 
		T[i] = S[i];
		ind[S[i]] = i;
	}

	vector<int> vec;
	for (int i = 0; i < n; i++)
		if (P[i] != i)
			vec.push_back(i);

	for (int i = 0; i <= m; i++) {
		swap(T[X[i]], T[Y[i]]);
		ind[T[X[i]]] = X[i];
		ind[T[Y[i]]] = Y[i];
		
		while (!vec.empty() && P[vec.back()] == vec.back()) vec.pop_back();

		if (vec.empty()) ans_A[i] = ans_B[i] = 0;
		else {
			int e = vec.back();

			ans_A[i] = ind[e];
			ans_B[i] = ind[P[e]];

			int a = e, b = P[e];
			swap(P[e], P[P[e]]);
			vec.push_back(a);
			vec.push_back(b);
		}

		swap(T[ans_A[i]], T[ans_B[i]]);
		ind[T[ans_A[i]]] = ans_A[i];
		ind[T[ans_B[i]]] = ans_B[i];
	}

	while (!vec.empty() && P[vec.back()] == vec.back()) vec.pop_back();
	return vec.empty();
}

int findSwapPairs(int N_, int S_[], int M_, int X_[], int Y_[], int P[], int Q[]) {
	n = N_, m = M_;
	for (int i = 0; i < n; i++)
		S[i] = S_[i];

	for (int i = 0; i < m; i++)
		X[i] = X_[i], Y[i] = Y_[i];

	bool flag = true;
	for (int i = 0; i < n; i++)
		if (S[i] != i)
			flag = false;
	
	if (flag) return 0;

	int l = 0, r = m - 1;
	while (l < r) {
		int mid = (l + r) >> 1;
		if (solve(mid)) r = mid;
		else l = mid + 1;
	}

	solve(l);
	
	for (int i = 0; i <= l; i++)
		P[i] = ans_A[i], Q[i] = ans_B[i];
	return l + 1;
}

Compilation message (stderr)

sorting.cpp: In function 'bool solve(int)':
sorting.cpp:18:23: warning: declaration of 'm' shadows a global declaration [-Wshadow]
   18 | inline bool solve(int m) {
      |                   ~~~~^
sorting.cpp:11:26: note: shadowed declaration is here
   11 | int X[MAXN], Y[MAXN], n, m, ans_A[MAXN], ans_B[MAXN], T[MAXN], P[MAXN], S[MAXN], ind[MAXN];
      |                          ^
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:63:69: warning: declaration of 'P' shadows a global declaration [-Wshadow]
   63 | int findSwapPairs(int N_, int S_[], int M_, int X_[], int Y_[], int P[], int Q[]) {
      |                                                                 ~~~~^~~
sorting.cpp:11:64: note: shadowed declaration is here
   11 | int X[MAXN], Y[MAXN], n, m, ans_A[MAXN], ans_B[MAXN], T[MAXN], P[MAXN], S[MAXN], ind[MAXN];
      |                                                                ^

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