Submission #778160

#	Time	Username	Problem	Language	Result	Execution time	Memory
778160		boris_mihov	Sorting (IOI15_sorting)	C++17	54 / 100	29 ms	456 KiB

sorting

#include "sorting.h"
#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>
#include <stack>

typedef long long llong;
const int MAXN = 200000 + 10;
const int INF  = 1e9;

int n;
int p[MAXN];
int pos[MAXN];

bool vis[MAXN];
std::vector <std::pair <int,int>> ops;
std::stack <std::pair <int,int>> st;

void getOps()
{
    ops.clear();
    std::fill(vis + 1, vis + 1 + n, false);

    for (int i = 1 ; i <= n ; ++i)
    {
        if (vis[i])
        {
            continue;
        }

        while (!st.empty())
        {
            st.pop();
        }

        int curr = i;
        while (!vis[curr])
        {
            vis[curr] = true;
            curr = p[curr];
        
            if (!vis[curr])
            {
                st.push({p[curr], p[i]});
            }
        }

        while (!st.empty())
        {
            ops.push_back(st.top());
            st.pop();
        }
    }
}

void makeSwap(int x, int y)
{
    std::swap(p[x], p[y]);
    pos[p[x]] = x;
    pos[p[y]] = y;
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) 
{
    n = N;
    for (int i = 1 ; i <= n ; ++i)
    {
        p[i] = S[i - 1] + 1;
    }

    for (int i = 1 ; i <= M ; ++i)
    {
        std::swap(p[X[i - 1] + 1], p[Y[i - 1] + 1]);
        getOps();

        if (ops.size() <= i)
        {
            while (ops.size() < i)
            {
                ops.push_back({1, 1});
            }

            break;
        }
    }

    for (int i = 1 ; i <= n ; ++i)
    {
        p[i] = S[i - 1] + 1;
        pos[p[i]] = i;
    }

    for (int i = 0 ; i < ops.size() ; ++i)
    {
        makeSwap(X[i] + 1, Y[i] + 1);
        P[i] = pos[ops[i].first] - 1;
        Q[i] = pos[ops[i].second] - 1;
        makeSwap(P[i] + 1, Q[i] + 1);
    }

    for (int i = 1 ; i <= n ; ++i)
    {
        assert(p[i] == i);
    }
    
    return ops.size();
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:78:24: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   78 |         if (ops.size() <= i)
      |             ~~~~~~~~~~~^~~~
sorting.cpp:80:31: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   80 |             while (ops.size() < i)
      |                    ~~~~~~~~~~~^~~
sorting.cpp:95:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   95 |     for (int i = 0 ; i < ops.size() ; ++i)
      |                      ~~^~~~~~~~~~~~
sorting.cpp:108:20: warning: conversion from 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
  108 |     return ops.size();
      |            ~~~~~~~~^~

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