Reorder Log Files

String

Easy

You have an array oflogs. Each log is a space delimited string of words.

For each log, the first word in each log is an alphanumericidentifier. Then, either:

• Each word after the identifier will consist only of lowercase letters, or;

• Each word after the identifier will consist only of digits.

We will call these two varieties of logsletter-logs_and_digit-logs. It is guaranteed that each log has at least one word after its identifier.

Reorder the logs so that all of the letter-logs come before any digit-log. The letter-logs are ordered lexicographically ignoring identifier, with the identifier used in case of ties. The digit-logs should be put in their original order.

Return the final order of the logs.

Example 1:

Input: 
["a1 9 2 3 1","g1 act car","zo4 4 7","ab1 off key dog","a8 act zoo"]
Output: 
["g1 act car","a8 act zoo","ab1 off key dog","a1 9 2 3 1","zo4 4 7"]

Note:

1. 0 <= logs.length <= 100

2. 3 <= logs[i].length <= 100

3. logs[i]is guaranteed to have an identifier, and a word after the identifier.

Analysis

Write a custom sort (compare function)

class Solution {
    public String[] reorderLogFiles(String[] logs) {
        Comparator<String> cmp = new Comparator<String>() {

            @Override
            public int compare(String log1, String log2) {
                int i1 = log1.indexOf(" ");
                int i2 = log2.indexOf(" ");

                char ch1 = log1.charAt(i1 + 1);
                char ch2 = log2.charAt(i2 + 1);

                if (Character.isDigit(ch1)) {
                    if (Character.isDigit(ch2)) {
                        return 0;
                    } else {
                        return 1;
                    }
                }  
                if (Character.isDigit(ch2)) {
                    return -1;
                } 
                int comp = log1.substring(i1 + 1).compareTo(log2.substring(i2 + 1));
                if (comp == 0) {
                    return log1.substring(0, i1).compareTo(log2.substring(0, i2));
                }
                return comp;
            }
        };
        Arrays.sort(logs, cmp);
        return logs;
    }
}

https://leetcode.com/problems/reorder-log-files/