Next Closest Time

Posted 2021-12-09 beiyeqingteng

Given a time represented in the format "HH:MM", form the next closest time by reusing the current digits. There is no limit on how many times a digit can be reused.

You may assume the given input string is always valid. For example, "01:34", "12:09" are all valid. "1:34", "12:9" are all invalid.

Example 1:

Input: "19:34"
Output: "19:39"
Explanation: The next closest time choosing from digits 1, 9, 3, 4, is 19:39, which occurs 5 minutes later. It is not 19:33, because this occurs 23 hours and 59 minutes later.
Example 2:

Input: "23:59"
Output: "22:22"
Explanation: The next closest time choosing from digits 2, 3, 5, 9, is 22:22. It may be assumed that the returned time is next day‘s time since it is smaller than the input time numerically.

 1 public class Test {
 2     public String nextClosestTime(String time) {
 3         char[] res = time.toCharArray();
 4         char[] digits = new char[] { res[0], res[1], res[3], res[4] };
 5         Arrays.sort(digits);
 6 
 7         // 从右到左对res进行操作，只要有当前最小单位时间的替换，返回替换后的时间
 8         res[4] = findNext(digits, res[4], ‘9‘);
 9         if (res[4] > time.charAt(4)) return String.valueOf(res);
10         
11         res[3] = findNext(digits, res[3], ‘5‘);
12         if (res[3] > time.charAt(3)) return String.valueOf(res);
13         
14         res[1] = res[0] == ‘2‘ ? findNext(digits, res[1], ‘3‘) : findNext(digits, res[1], ‘9‘);
15         if (res[1] > time.charAt(1)) return String.valueOf(res);
16         
17         res[0] = findNext(digits, res[0], ‘2‘);
18         return String.valueOf(res);
19     }
20 
21     private char findNext(char[] digits, char cur, char upper) {
22         if (cur == upper) return digits[0];
23         // 找到cur的位置，然后加1得到下一个位置
24         int pos = Arrays.binarySearch(digits, cur) + 1;
25         // 如果下一个位置的数还是原来的数，或者超过了上限数，前进到再下一个
26         while (pos < 4 && (digits[pos] == cur || digits[pos] > upper)) {
27             pos++;
28         }
29         return pos == 4 ? digits[0] : digits[pos];
30     }
31 }