Finding missing words in string

Pulkit :

I am trying to solve a problem of finding missing words in a string.

For example:
Input
String 1 = "I love programming, pizza, coke and chips";
String 2 = "I programming, chips";
Required Output
Missing words = "love pizza coke";

Note: the order of output has to be same (this is where I am messing up)

what I have so far, but I am getting wrong results.

public static List<String> findWord(String s, String t) {
    HashSet<String> missingWords = new HashSet<>();
    String[] words = s.split(" ");
    for(int i=0; i < words.length; i++) {
        if (!t.contains(words[i])) {
            missingWords.add(words[i]);
        }
    }
    List<String> ans = new ArrayList<String>();
    for (String str: missingWords) {
        ans.add(str);
    }

    return ans;
}

Tim Biegeleisen :

I would approach this by splitting both input strings, stripping off punctuation, and then walking down each array of words, in the original order. When encountering a match, both lists advance. When there is no match, the original list advances, but the second list does not, and we also record the original word as not having found a match.

The key point here is that we use an ArrayList, which maintains insertion order, while traversing.

String input = "I love programming, pizza, coke and chips";
String other = "I programming, chips";
String[] parts = input.replaceAll("[,.;-]", "").split("\\s");
String[] otherparts = other.replaceAll("[,.;-]", "").split("\\s");
List<String> missing = new ArrayList<>();
int pnt = 0;
for (int i=0; i < parts.length; ++i) {
    if (parts[i].equals(otherparts[pnt])) {
        ++pnt;
    }
    else {
        missing.add(parts[i]);
    }
}

System.out.println(Arrays.toString(parts));
System.out.println(Arrays.toString(missing.toArray()));

[I, love, programming, pizza, coke, and, chips]
[love, pizza, coke, and]

Demo

Demo added for informational purposes only. Do not rely on it for production use.