Formatted question description: https://leetcode.ca/all/1736.html

# 1736. Latest Time by Replacing Hidden Digits

## Level

Easy

## Description

You are given a string `time`

in the form of `hh:mm`

, where some of the digits in the string are hidden (represented by `?`

).

The valid times are those inclusively between `00:00`

and `23:59`

.

Return *the latest valid time you can get from time by replacing the hidden digits*.

**Example 1:**

**Input:** time = “2?:?0”

**Output:** “23:50”

**Explanation:** The latest hour beginning with the digit ‘2’ is 23 and the latest minute ending with the digit ‘0’ is 50.

**Example 2:**

**Input:** time = “0?:3?”

**Output:** “09:39”

**Example 3:**

**Input:** time = “1?:22”

**Output:** “19:22”

**Constraints:**

`time`

is in the format`hh:mm`

.- It is guaranteed that you can produce a valid time from the given string.

## Solution

First consider the hour. The hour must be in range [00, 23]. Replace the hidden digits with the maximum possible value in the range. Then consider the minute. The minute must be in range [00, 59]. The two digits of the minute should be replaced with the maximum possible digit, which are 5 and 9 respectively. Finally, return the replaced time.

```
class Solution {
public String maximumTime(String time) {
char[] array = time.toCharArray();
if (array[0] == '?') {
if (array[1] == '?') {
array[0] = '2';
array[1] = '3';
} else {
if (array[1] <= '3')
array[0] = '2';
else
array[0] = '1';
}
}
if (array[1] == '?') {
if (array[0] == '2')
array[1] = '3';
else
array[1] = '9';
}
if (array[3] == '?')
array[3] = '5';
if (array[4] == '?')
array[4] = '9';
return new String(array);
}
}
```