Disheartened

beauf wrote: »

Converting or validating time/date, numbers especially from legacy systems, where they are strings, padded with spaces or unknown non visible characters, and can be different lengths, is pretty common for me.

I actually enjoy solving these kind of problems more than just routine work. But I've never done them in a interview situation.

public String solve(int A, int B, int C, int D, int E, int F) {
  int[] d = {A, B, C, D, E, F};
  Arrays.sort(d);
  if (d[4] < 6) { // 2nd largest digit is smaller 6, we can just fill up
    if (10 * d[0] + d[1] < 24)
      return "" + d[0] + d[1] + ":" + d[2] + d[3] + ":" + d[4] + d[5];
    else
      return "impossible";
  } else if (d[3] < 6) { // 3rd largest digit is smaller 6, put 2nd largest in 4th position
    if (10 * d[0] + d[1] < 24)
      return "" + d[0] + d[1] + ":" + d[2] + d[4] + ":" + d[3] + d[5];
    else
      return "impossible";
  } else if (d[2] < 6) { // 4th largest digit is smaller 6, put 3rd largest in 2nd position
    if (10 * d[0] + d[3] < 24)
      return "" + d[0] + d[3] + ":" + d[1] + d[4] + ":" + d[2] + d[5];
    else
      return "impossible";
  } else {
      return "impossible";
  }
}

Pelvis wrote: »

Slightly off but still on topic. I have an opportunity to move to a dev role in my current company, it's in the early stages of an expansion and there are going to be plenty of new systems built in-house.

14ned wrote: »

time_from_digits() could be compressed into less than six lines, but it's easier to read this way:

#include <time.h>
#include <limits.h>
#include <stdio.h>

int digit(const char *i, int limit)
{
    int ret=(i[0]-'0')*10+(i[1]-'0');
    return (ret>=limit) ? -1 : ret;
}

const char *time_from_digits(const char *input)
{
    struct tm t{digit(input+4, 60), digit(input+2, 60), digit(input+0, 24), 1, 1, 1970, 0, 0, 0, 0, 0};
    if(t.tm_sec<0 || t.tm_min<0 || t.tm_hour<0 || mktime(&t)<0) return "null";
    char *r=asctime(&t)+11;
    r[8]=0;
    return r;
}

int main(void)
{
    printf("%s\n", time_from_digits("122304"));
    printf("%s\n", time_from_digits("000000"));
    printf("%s\n", time_from_digits("235960"));
    printf("%s\n", time_from_digits("240100"));
    return 0;
}

Obviously this is a terrible implementation which nobody should use, but the key is to make use of the standard library functions to do the validation and printing of times. The reason we need to clamp the values by hand is because asctime() is too clever, and automagically "repairs" invalid input silently on your behalf. Any language which is not C would not do such a stupid behaviour, so the above would be much shorter and simpler on say Python, or even C++.

You can see the above running correctly at https://wandbox.org/permlink/5p4EqctOdfFx8YAh

Niall

def time_from_digets(digits):
    digits.sort()

    if digits[0] > 2:
        return None

    elif digits[0] == 2:
        if digits[4] > 5:
            digits[3], digits[4] = digits[4], digits[3]

        if digits[1] > 3 or digits[2] > 5 or digits[4] > 5:
            return None
        return digits
    else:
        if digits[2] > 5:
            digits[1], digits[2] = digits[2], digits[1]
        if digits[4] > 5:
            if digits[3] < 6:
                digits[3], digits[4] = digits[4], digits[3]
            else:
                digits[1], digits[4] = digits[4], digits[1]
                digits[1], digits[3] = digits[3], digits[1]
        if digits[2] > 5 or digits[4] > 5:
            return None
        return digits

print time_from_digets([0,0,0,7,8,9])
print time_from_digets([0,0,0,7,8,9]) == [0, 7, 0, 8, 0, 9] 
print time_from_digets([2,4,5,9,5,9])
print time_from_digets([2,4,5,9,5,9]) == None
print time_from_digets([1,2,2,6,0,4])
print time_from_digets([1,2,2,6,0,4]) == [0, 1, 2, 2, 4, 6]
print time_from_digets([1,2,2,6,6,6])
print time_from_digets([1,2,2,6,6,6]) == [1, 6, 2, 6, 2, 6]

if (sorted[0] * 10 + sorted[1] > 23)
  return null

check = low_numbers.length - high_numbers.length
if (check < 0)
  return null

smacl wrote: »

If I'm honest, the reason I raised the six lines of C thing is that the OP came on here as a relatively inexperienced programmer looking for reassurances that a problem is non-trivial and you tell them the opposite. Poor form IMHO.

Deleted User wrote: »

You've skipped a lot of the complications. You can't just sort the array.

Am I the only one who has actually finished this? I was expecting more solutions.