Alg.16 Reverse Words In String

From algoexpert.io

In this problem, given a string of words seperated by one or more whitespaces. We need to write a function reverse these words. Basically, the idea is seperate all the words by the whitespaces. Then, we simply reverse them. Here is the implementation:

public String reverseWordsInString(String string) {
    List<String> words = new ArrayList<>();
        int curStart = 0;
        for (int i = 0; i < string.length(); i++) {
            char c = string.charAt(i);
            if (c  == ' ') {
                words.add(string.substring(curStart, i));
                words.add(" ");
                curStart = i + 1;
            } else {
                continue;
            }
        }
        words.add(string.substring(curStart));
        Collections.reverse(words);
    return String.join("", words);
  }

Another way is to first reverse all the characters within this string, then we reverse each string back.

Time complexity: O(n); Space complexity: O(n)

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