Submission #170042

#	Time	Username	Problem	Language	Result	Execution time	Memory
170042		AlexLuchianov	Sorting (IOI15_sorting)	C++14	0 / 100	5 ms	888 KiB

sorting

#include "sorting.h"
#include <iostream>
#include <vector>
#include <cassert>


int const nmax = 1000000;
int init[1 + nmax], n;
int v[1 + nmax], frec[1 + nmax], f[1 + nmax], pos[1 + nmax];
int xswap[1 + nmax], yswap[1 + nmax];
int pswap[1 + nmax], qswap[1 + nmax];

bool valid(int target){
  for(int i = 0; i < n; i++)
    v[i] = init[i];
  for(int i = 0; i < target; i++) {
    std::swap(v[xswap[i]], v[yswap[i]]);
    std::swap(v[pswap[i]], v[qswap[i]]);
  }

  /*
  std::cout << '\n';
  for(int i = 0; i < target; i++)
    std::cout << v[i] << " ";
  std::cout << '\n';
  */

  for(int i = 0; i < target; i++)
    if(v[i] != i)
      return false;
  return true;
}

bool tryit(int target){
  for(int i = 0; i < n; i++)
    f[i] = i;
  for(int i = target - 1 ; 0 <= i; i--)
    std::swap(f[xswap[i]], f[yswap[i]]);

  for(int i = 0; i < n; i++)
    v[i] = init[i];
  for(int i = 0; i < n; i++)
    pos[v[i]] = i;

  std::vector<int> q;
  for(int i = 0; i < n; i++)
    if(f[i] != v[i])
      q.push_back(i);

  for(int i = 0; i < target; i++){
    /*
    for(int j = 0; j < n; j++)
      std::cout << v[j] << " ";
    std::cout << '\n';
    for(int j = 0; j < n; j++)
      std::cout << f[j] << " ";
    std::cout << '\n';
    for(int j = 0; j < n; j++)
      std::cout << pos[j] << " ";
    std::cout << '\n';
    std::cout << '\n';
    */

    std::swap(v[xswap[i]], v[yswap[i]]);
    pos[v[xswap[i]]] = xswap[i];
    pos[v[yswap[i]]] = yswap[i];

    std::swap(f[xswap[i]], f[yswap[i]]);

    /*
    for(int j = 0; j < n; j++)
      std::cout << v[j] << " ";
    std::cout << '\n';
    for(int j = 0; j < n; j++)
      std::cout << f[j] << " ";
    std::cout << '\n';
    for(int j = 0; j < n; j++)
      std::cout << pos[j] << " ";
    std::cout << '\n';
    std::cout << '\n' << '\n';
    */

    while(0 < q.size()){
      int e = q.back();
      q.pop_back();
      //std::cout << "q:" << e << '\n';

      if(f[e] == v[e]){
        continue;
      } else {
        pswap[i] = e;
        qswap[i] = pos[f[e]];
        std::swap(v[pswap[i]], v[qswap[i]]);
        pos[v[pswap[i]]] = pswap[i];
        pos[v[qswap[i]]] = qswap[i];
       // std::cout << "&" << e << " " << pos[f[e]] << '\n';
        break;
      }
    }
  }

  /*
  for(int i = 0; i < n; i++)
    std::cout << v[i] << " ";
  std::cout << '\n';
  */

  while(0 < q.size()){
    int e = q.front();
    q.pop_back();
    if(f[e] == v[e])
      continue;
    else
      return false;
  }
  //std::cout << "|";

  return true;
}

int binarysearch(int from, int to){
  if(from < to){
    int mid = (from + to) / 2;
    if(tryit(mid))
      return binarysearch(from, mid);
    else
      return binarysearch(mid + 1, to);
  } else
    return from;
}

int findSwapPairs(int N_, int S_[], int M, int X_[], int Y_[], int P[], int Q[]) {
  n = N_;
  for(int i = 0; i < n; i++)
    init[i] = S_[i];
  for(int i = 0; i < M; i++)
    xswap[i] = X_[i];
  for(int i = 0; i < M; i++)
    yswap[i] = Y_[i];

  tryit(3);
  int steps = 3;
  /*
  int steps = binarysearch(0, M);
  tryit(steps);

  */
  for(int i = 0; i < steps; i++)
    P[i] = pswap[i];
  for(int i = 0; i < steps; i++)
    Q[i] = qswap[i];

  //std::cout << steps << '\n';

  if(valid(steps) == 0)
    assert(1 < 0);

	return steps;
}

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