Largest Time for Given Digits

LeetCode Q 949 - Largest Time for Given Digits

Given an array of 4 digits, return the largest 24 hour time that can be made.
The smallest 24 hour time is 00:00, and the largest is 23:59. Starting from 00:00, a time is larger if more time has elapsed since midnight.
Return the answer as a string of length 5. If no valid time can be made, return an empty string.

Example 1: Input: [1,2,3,4] ; Output: "23:41"
Example 2: Input: [5,5,5,5] ; Output: ""

Note:

• A.length == 4
• 0 <= A[i] <= 9

Solution

Code:

public String largestTimeFromDigits(int[] A) {
  String ans = "";
  for (int i = 0; i < 4; i++) {
    for (int j = 0; j < 4; j++) {
      for (int k = 0; k < 4; k++) {
        if (i == j || i == k || j == k) continue;
        String h = "" + A[i] + A[j];
        String m = "" + A[k] + A[6 - i - j - k]; // 0+1+2+3=6
        String t = h + ":" + m;

        if (h.comparTo("24") < 0 && m.compareTo("60") < 0 && ans.compareTo(t) < 0)
          ans = t;
      }
    }
  }

  return ans;
}