UVa 11634 - Generate random numbers

Accepted date: 2014-01-21
Ranking (as of 2014-01-21): 104 out of 579
Language: C++

/*
  UVa 11634 - Generate random numbers

  To build using Visual Studio 2012:
    cl -EHsc -O2 UVa_11634_Generate_random_numbers.cpp
*/

#include <cstdio>
#include <cstring>

const int a0_max = 10000 - 1;
bool numbers[a0_max + 1]; // numbers[i] is true if i has already been produced

int main()
{
  while (true) {
    int a;
    scanf("%d", &a);
    if (!a)
      break;
    memset(numbers, 0, sizeof(numbers));
    int nr = 0;
    while (true) {
      if (numbers[a])
        break;
      numbers[a] = true;
      a *= a;
      a /= 100;
      a %= 10000;
      nr++;
    }
    printf("%d\n", nr);
  }
  return 0;
}