Medium String Sort



1451. Rearrange Words in a Sentence


Given a sentence text (A sentence is a string of space-separated words) in the following format:

  • First letter is in upper case.
  • Each word in text are separated by a single space.

Your task is to rearrange the words in text such that all words are rearranged in an increasing order of their lengths. If two words have the same length, arrange them in their original order.

Return the new text following the format shown above.

Example 1:

Input: text = "Leetcode is cool"
Output: "Is cool leetcode"
Explanation: There are 3 words, "Leetcode" of length 8, "is" of length 2 and "cool" of length 4.
Output is ordered by length and the new first word starts with capital letter.

Example 2:

Input: text = "Keep calm and code on"
Output: "On and keep calm code"
Explanation: Output is ordered as follows:
"On" 2 letters.
"and" 3 letters.
"keep" 4 letters in case of tie order by position in original text.
"calm" 4 letters.
"code" 4 letters.

Example 3:

Input: text = "To be or not to be"
Output: "To be or to be not"


  • text begins with a capital letter and then contains lowercase letters and single space between words.
  • 1 <= text.length <= 10^5


Sort the array first, and then join them together. Since array.sort is a stable sort, we can keep them in the original order if the length are same. It can also be achieved by using Prioirty Queue, but we need to have a time stamp or order to compare when poll from the queue.

class Solution {
    public String arrangeWords(String text) {
        String[] strarr = text.toLowerCase().split(" ");
        Arrays.sort(strarr, (a,b) ->  a.length() - b.length());
        String result = String.join(" ", strarr);
        return Character.toUpperCase(result.charAt(0)) + result.substring(1);