Freshman's Database

input/code.cpp: In function 'int main()':
input/code.cpp:16:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < n; ++i) {
                   ~~^~~
input/code.cpp:26:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       if (visited[latest] == i) {

#include <iostream>
#include <vector>

int main(void) {
  unsigned int n = 0;

  std::ios_base::sync_with_stdio(false);

  std::cin >> n;

  std::vector<unsigned int> array(n + 1);
  std::vector<int> visited(n + 1, -1);

  array[0] = 0;

  for (int i = 0; i < n; ++i) {
    std::cin >> array[i + 1];
  }

  unsigned int cycles = 0;

  for (unsigned int i = 1; i < (n + 1); ++i) {
    unsigned int latest = i;
    
    while (true) {
      if (visited[latest] == i) {
        cycles += 1;
        //std::cout << "cycle " << i << " " << latest << std::endl;
        break;
      }
      
      // Already would have seen this cycle
      if (visited[latest] > -1) {
        //std::cout << "skip " << i << " " << latest << " " << visited[latest] << std::endl;
        break;
      }
      
      visited[latest] = i;
      latest = array[latest];
    }
  }

  std::cout << cycles << std::endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED