Submission #970671

#	Time	Username	Problem	Language	Result	Execution time	Memory
970671		nguyentunglam	Sorting (IOI15_sorting)	C++17	100 / 100	203 ms	23604 KiB

sorting

#include "sorting.h"
#ifdef ngu
#include "grader.cpp"
#endif // ngu
#include<bits/stdc++.h>
using namespace std;

const int N = 2e5 + 10;

int a[2][N], pos[2][N];

int cnt;

int findSwapPairs(int n, int s[], int m, int x[], int y[], int p[], int q[]) {
  int l = 0, r = m, ans = -1;

  auto check = [&] (int rounds) {
    for(int i = 0; i < n; i++) a[0][i] = a[1][i] = s[i];
    for(int i = 0; i < rounds; i++) {
      swap(a[1][x[i]], a[1][y[i]]);
    }
    cnt = 0;

    auto Swap = [&] (int j, int val1, int val2) {
      if (j == 0) {
        p[cnt] = pos[j][val1];
        q[cnt] = pos[j][val2];
      }
      swap(pos[j][val1], pos[j][val2]);
      swap(a[j][pos[j][val1]], a[j][pos[j][val2]]);
    };

    for(int i = 0; i < n; i++) pos[0][a[0][i]] = i, pos[1][a[1][i]] = i;
    for(int i = 0; i < n; i++) if (a[1][i] != i) {
      if (cnt >= rounds) {
        return false;
      }

      Swap(0, a[0][x[cnt]], a[0][y[cnt]]);

      Swap(0, a[1][i], i);
      cnt++;

      Swap(1, a[1][i], i);
    }

    for(int i = cnt; i < rounds; i++) p[i] = q[i] = 0;

    return true;
  };

  while (l <= r) {
    int mid = l + r >> 1;
    if (check(mid)) {
      ans = mid;
      r = mid - 1;
    } else l = mid + 1;
  }

  assert(ans != -1);

  check(ans);

  return ans;
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:53:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   53 |     int mid = l + r >> 1;
      |               ~~^~~

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