Submission #1059203

#	Time	Username	Problem	Language	Result	Execution time	Memory
1059203		andrei_iorgulescu	Sorting (IOI15_sorting)	C++14	100 / 100	163 ms	33168 KiB

sorting

#include <bits/stdc++.h>
#include "sorting.h"
#warning That's not FB, that's my FB

using namespace std;

int n;
bool viz[200005];
vector<int> lols;
vector<vector<int>> cicli;
vector<int> cur;

void dfs(int nod)
{
    viz[nod] = true;
    cur.push_back(nod);
    if (!viz[lols[nod]])
        dfs(lols[nod]);
}

int cnt_cyc(vector<int> s)
{
    cicli.clear();
    lols = s;
    memset(viz, 0, sizeof(viz));
    for (int i = 0; i < n; i++)
    {
        if (!viz[i])
        {
            cur.clear();
            dfs(i);
            cicli.push_back(cur);
        }
    }
    return cicli.size();
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[])
{
    n = N;
    int st = -1, pas = 1 << 17;
    while (pas != 0)
    {
        if (st + pas <= M)
        {
            vector<int> s(N);
            for (int i = 0; i < N; i++)
                s[i] = S[i];
            for (int i = 0; i < st + pas; i++)
                swap(s[X[i]], s[Y[i]]);
            if (n - cnt_cyc(s) > st + pas)
                st += pas;
        }
        pas /= 2;
    }
    st++;
    int ans = st;
    vector<pair<int,int>> req_swaps;
    vector<int> s(N);
    for (int i = 0; i < N; i++)
        s[i] = S[i];
    for (int i = 0; i < st + pas; i++)
        swap(s[X[i]], s[Y[i]]);
    int useless = cnt_cyc(s);
    for (int i = 0; i < useless; i++)
        for (int j = (int)cicli[i].size() - 2; j >= 0; j--)
            req_swaps.push_back({cicli[i].back(),cicli[i][j]});
    vector<int> pos(N);
    for (int i = 0; i < N; i++)
        pos[S[i]] = i;
    for (int i = req_swaps.size(); i < ans; i++)
        P[i] = Q[i] = 0;
    for (int i = 0; i < req_swaps.size(); i++)
    {
        swap(S[X[i]],S[Y[i]]);
        pos[S[X[i]]] = X[i];
        pos[S[Y[i]]] = Y[i];
        P[i] = pos[req_swaps[i].first];
        Q[i] = pos[req_swaps[i].second];
        swap(S[P[i]],S[Q[i]]);
        pos[S[P[i]]] = P[i];
        pos[S[Q[i]]] = Q[i];
    }
    return ans;
}

///;gimme 1200 +constructive +greedy (nice one still)

Compilation message (stderr)

sorting.cpp:3:2: warning: #warning That's not FB, that's my FB [-Wcpp]
    3 | #warning That's not FB, that's my FB
      |  ^~~~~~~
sorting.cpp: In function 'int cnt_cyc(std::vector<int>)':
sorting.cpp:35:22: warning: conversion from 'std::vector<std::vector<int> >::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   35 |     return cicli.size();
      |            ~~~~~~~~~~^~
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:71:32: warning: conversion from 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   71 |     for (int i = req_swaps.size(); i < ans; i++)
      |                  ~~~~~~~~~~~~~~^~
sorting.cpp:73:23: 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 |     for (int i = 0; i < req_swaps.size(); i++)
      |                     ~~^~~~~~~~~~~~~~~~~~

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