Problem

Given a list of 24-hour clock time points in “HH:MM” format, return the minimum minutes difference between any two time-points in the list.

Example 1:

Input: timePoints = ["23:59","00:00"]
Output: 1

Example 2:

Input: timePoints = ["00:00","23:59","00:00"]
Output: 0

Constraints:

• 2 <= timePoints.length <= 2 * 104
• timePoints[i] is in the format “HH:MM”.

Java Solution

class Solution {
    public int findMinDifference(List<String> timePoints) {
        int[] exist = new int[24 * 60];
        for (String time : timePoints) {
            int minutes = Integer.parseInt(time.substring(0, 2)) * 60 + Integer.parseInt(time.substring(3, 5));
            if (exist[minutes] != 0) {
                return 0;
            } else {
                exist[minutes] = 1;
            }
        }

        int prev = -1;
        int res = Integer.MAX_VALUE, start = Integer.MAX_VALUE, end = Integer.MIN_VALUE;
        for (int i = 0; i < 24 * 60; i++) {
            if (exist[i] == 1) {
                if (prev == -1) {
                    prev = i;
                } else {
                    res = Math.min(res, i - prev);
                }
                prev = i;
                start = Math.min(start, i);
                end = Math.max(end, i);
            }
        }
        return Math.min(res, 24 * 60 - (end - start));
    }
}