Submission #1172018

#	Time	Username	Problem	Language	Result	Execution time	Memory
1172018		fryingduc	Machine (IOI24_machine)	C++20	10 / 100	4 ms	440 KiB

machine

#include "machine.h"

#include "bits/stdc++.h"

using namespace std;

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

vector<int> find_permutation(int N) {
  int n = N;
  if (n & 1) {
    vector<int> a(n);
    iota(a.begin(), a.end(), 0);
    vector<int> b = use_machine(a);
    int x = 0;
    for (int i = 0; i < n; ++i) {
      bool flag = 0;
      for (int j = 0; j < n; ++j) {
        if (i == j) continue;
        if ((b[i] ^ b[j]) == 1) {
          flag = 1;
          break;
        }
      }
      if (!flag) {
        x = b[i] ^ (n - 1);
        break;
      }
    }
    vector<int> rev(n);
    for (int i = 0; i < n; ++i) {
      b[i] ^= x;
    }
    return b;
  } else {
    vector<int> a(n);
    iota(a.begin(), a.end(), 1);
    a[n - 1] = n + 2;
    vector<int> b = use_machine(a);
    for (int x = 0; x < 256; ++x) {
      vector<int> c(n + 1);
      bool flag = 1;
      for (int i = 0; i < n; ++i) {
        int t = b[i] ^ x;
        if (t > n + 2) {
          flag = 0;
          break;
        } else if (t == n + 2) {
          if (c[n]) {
            flag = 0;
            break;
          }
          c[n] = 1;
        } else {
          if (c[t]) {
            flag = 0;
            break;
          }
          c[t] = 1;
        }
      }
      if (flag) {
        for (auto &i : b) {
          i ^= x;
          if (i == n + 2) i = n;
          --i;
        }
        return b;
      }  
    }
  }
}

Compilation message (stderr)

machine.cpp: In function 'std::vector<int> find_permutation(int)':
machine.cpp:76:1: warning: control reaches end of non-void function [-Wreturn-type]
   76 | }
      | ^

• Subtask 0: 0 / 0
• Subtask 1: 0 / 7
• Subtask 2: 0 / 12
• Subtask 3: 0 / 19
• Subtask 4: 0 / 21
• Subtask 5: 10 / 10
• Subtask 6: 0 / 31