Submission #1088456

#	Time	Username	Problem	Language	Result	Execution time	Memory
1088456		Pacybwoah	Sorting (IOI15_sorting)	C++17	54 / 100	22 ms	676 KiB

sorting

#include "sorting.h"
#include<iostream>
#include<vector>
#include<algorithm>
#include<utility>
#include<cassert>
using namespace std;
namespace{
	struct DSU{
		vector<int> dsu, sz;
		DSU(int n){
			dsu.resize(n + 1);
			sz.resize(n + 1);
			for(int i = 1; i <= n; i++) dsu[i] = i, sz[i] = 1;
		}
		int query(int x){
			if(x == dsu[x]) return x;
			dsu[x] = query(dsu[x]);
			return dsu[x];
		}
		void unite(int a, int b){
			a = query(a);
			b = query(b);
			if(a == b) return;
			if(sz[a] < sz[b]) swap(a, b);
			dsu[b] = a;
			sz[a] += sz[b];
		}
	};
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	int n = N;
	vector<int> pos(n);
	for(int i = 0; i < n; i++) pos[S[i]] = i;
	vector<int> vec(n);
	bool flag1 = 1;
	for(int i = 0; i < n; i++) if(S[i] != i) flag1 = 0;
	if(flag1) return 0;
	for(int i = 0; i < n; i++){
		for(int j = 0; j < n; j++) vec[j] = S[j], pos[S[j]] = j;
		vector<int> oripos;
		for(int j = 0; j < n; j++){
			swap(vec[X[j]], vec[Y[j]]);
			swap(pos[vec[X[j]]], pos[vec[Y[j]]]);
			if(j < i){
				swap(vec[P[j]], vec[Q[j]]);
				swap(pos[vec[P[j]]], pos[vec[Q[j]]]);
			}
			if(j == i){
				oripos = pos;
				bool flag = 0;
			}
		}
		P[i] = oripos[i];
		Q[i] = oripos[vec[i]];
		for(int j = 0; j < n; j++) vec[j] = S[j];
		for(int j = 0; j <= i; j++){
			swap(vec[X[i]], vec[Y[i]]);
			swap(vec[P[i]], vec[Q[i]]);
		}
		bool flag = 1;
		for(int j = 0; j < n; j++) if(j != vec[j]) flag = 0;
		if(flag) return i + 1;
	}
	return n;
    /*int l = 0, r = M;
	while(l < r){
		int mid = (l + r) >> 1;
		DSU dsu(n);
		vector<int> vec(n);
		for(int i = 0; i < n; i++) vec[i] = S[i];
		for(int i = 0; i < mid; i++) swap(vec[X[i]], vec[Y[i]]);
		for(int i = 0; i < n; i++) dsu.unite(vec[i], i);
		vector<bool> vis(n);
		int cc = 0;
		for(int i = 0; i < n; i++){
			if(!vis[dsu.query(i)]){
				vis[dsu.query(i)] = 1;
				cc++;
			}
		}
		if(n - cc <= mid) r = mid;
		else l = mid + 1;
	}
	DSU dsu(n);
	vector<int> pos(n);
	for(int i = 0; i < l; i++) swap(S[X[i]], S[Y[i]]);
	for(int i = 0; i < n; i++) dsu.unite(i, S[i]), pos[S[i]] = i;
	vector<vector<int>> children(n);
	for(int i = 0; i < n; i++) children[dsu.query(i)].push_back(i);
	int cur = 0;
	for(int i = 0; i < n; i++){
		if((int)children[i].size() >= 2){
			int sz = children[i].size();
			for(int j = 0; j < sz - 1; j++){
				int id = children[i][j];
				P[cur] = id;
				Q[cur] = pos[id];
				swap(S[P[cur]], S[Q[cur]]);
				swap(pos[S[P[cur]]], pos[S[Q[cur]]]);
				cur++;
			}
		}
	}
	while(cur < l - 1){
		P[cur] = 0;
		Q[cur] = 0;
		cur++;
	}
	return l;*/
}
// g++ -std=c++17 -Wall -Wextra -fsanitize=undefined -fsanitize=address -Wshadow -o run sorting.cpp grader.cpp

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:52:10: warning: unused variable 'flag' [-Wunused-variable]
   52 |     bool flag = 0;
      |          ^~~~
sorting.cpp:32:39: warning: unused parameter 'M' [-Wunused-parameter]
   32 | int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
      |                                   ~~~~^

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