Submission #985116

#	Time	Username	Problem	Language	Result	Execution time	Memory
985116		LucaIlie	Sorting (IOI15_sorting)	C++17	100 / 100	202 ms	25376 KiB

sorting

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

using namespace std;

const int MAX_N = 2e5;
int t[MAX_N], perm[MAX_N], vis[MAX_N], pos[MAX_N];

vector<pair<int, int>> sol;
int getR( int n, int s[], int k, int x[], int y[], int p[], int q[] ) {
    for ( int i = 0; i < n; i++ )
        t[i] = i, pos[i] = i;

    for ( int i = 0; i < k; i++ ) {
        swap( t[pos[x[i]]], t[pos[y[i]]] );
        swap( pos[x[i]], pos[y[i]] );
    }
    for ( int i = 0; i < n; i++ )
        perm[t[i]] = s[i];//, printf( "%d ", t[i] );
    //printf( "\n\n" );

    for ( int i = 0; i < n; i++ )
        vis[i] = false;

    sol.clear();
    for ( int i = 0; i < n; i++ ) {
        //printf( "%d ", perm[i] );
        if ( vis[i] )
            continue;

        int j = i;
        vector<pair<int, int>> v;
        do {
            vis[j] = true;
            if ( perm[j] != j && j != i )
                v.push_back( { j, perm[j] } );
            j = perm[j];
        } while ( j != i );
        //reverse( v.begin(), v.end() );
        for ( pair<int, int> swp: v )
            sol.push_back( swp );
    }
    //printf( "\n" );

    return sol.size();
}

int findSwapPairs( int n, int s[], int m, int x[], int y[], int p[], int q[] ) {
    int l = -1, r = m;
    while ( r - l > 1 ) {
        int k = (l + r) / 2;

        int rr = getR( n, s, k, x, y, p, q );
        //printf( "%d %d\n", k, rr );
        if ( rr > k )
            l = k;
        else
            r = k;
    }

    getR( n, s, r, x, y, p, q );
    for ( int i = 0; i < n; i++ )
        pos[s[i]] = i;
    for ( int i = 0; i < r; i++ ) {
        //for ( int j = 0; j < n; j++ )
          //  printf( "%d ", pos[j] );
        //printf( "\n" );
        swap( pos[s[x[i]]], pos[s[y[i]]] );
        swap( s[x[i]], s[y[i]] );
        //for ( int j = 0; j < n; j++ )
          //  printf( "%d ", pos[j] );
        //printf( "\n" );
        if ( i < sol.size() ) {
            //printf( "%d %d\n", sol[i].first, sol[i].second );
            p[i] = pos[sol[i].first];
            q[i] = pos[sol[i].second];
            swap( pos[sol[i].first], pos[sol[i].second] );
            swap( s[p[i]], s[q[i]] );
        } else {
            p[i] = 0;
            q[i] = 0;
        }

        //for ( int j = 0; j < n; j++ )
          //  printf( "%d ", s[j] );
        //printf( "\n\n" );
    }

    //for ( int i = 0; i < n; i++ )
  //      cout << s[i] << "\n";

    return r;
}

Compilation message (stderr)

sorting.cpp: In function 'int getR(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:45:20: warning: conversion from 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   45 |     return sol.size();
      |            ~~~~~~~~^~
sorting.cpp:10:56: warning: unused parameter 'p' [-Wunused-parameter]
   10 | int getR( int n, int s[], int k, int x[], int y[], int p[], int q[] ) {
      |                                                    ~~~~^~~
sorting.cpp:10:65: warning: unused parameter 'q' [-Wunused-parameter]
   10 | int getR( int n, int s[], int k, int x[], int y[], int p[], int q[] ) {
      |                                                             ~~~~^~~
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:73:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   73 |         if ( i < sol.size() ) {
      |              ~~^~~~~~~~~~~~

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