Reformat Date LeetCode Solution

·1 min
Leetcode

Given a `date` string in the form `Day Month Year`, where:

• `Day` is in the set `{"1st", "2nd", "3rd", "4th", ..., "30th", "31st"}`.
• `Month` is in the set `{"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}`.
• `Year` is in the range `[1900, 2100]`.

Convert the date string to the format `YYYY-MM-DD`, where:

• `YYYY` denotes the 4 digit year.
• `MM` denotes the 2 digit month.
• `DD` denotes the 2 digit day.

Example 1:

Input: date = “20th Oct 2052” Output: “2052-10-20”

Example 2:

Input: date = “6th Jun 1933” Output: “1933-06-06”

Example 3:

Input: date = “26th May 1960” Output: “1960-05-26”

Constraints:

• The given dates are guaranteed to be valid, so no error handling is necessary.

Solution in Java #

class Solution { public String reformatDate(String date) {

``````    String\[\] monthArray = {"", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
List<String> list = Arrays.asList(monthArray);

String\[\] split = date.split(" ");
String day = split\[0\].replaceAll("\\\\D", "");
// \\D means "not digit" in regex
int month = list.indexOf(split\[1\]);

// "%02d" means if length of the argument is less than 2 then pad with a zero
return split\[2\] + "-" + String.format("%02d", month) + "-" + String.format("%02d", Integer.parseInt(day));
}
``````

}