[LeetCode] 745. Prefix and Suffix Search

Problem

Given many words, words[i] has weight i.

Design a class WordFilter that supports one function, WordFilter.f(String prefix, String suffix). It will return the word with given prefix and suffix with maximum weight. If no word exists, return -1.

Examples:

Input:
WordFilter(["apple"])
WordFilter.f("a", "e") // returns 0
WordFilter.f("b", "") // returns -1

Note:
words has length in range [1, 15000].
For each test case, up to words.length queries WordFilter.f may be made.
words[i] has length in range [1, 10].
prefix, suffix have lengths in range [0, 10].
words[i] and prefix, suffix queries consist of lowercase letters only.

Soluton (HashMap)

class WordFilter {

    Map map = new HashMap<>(); 
    public WordFilter(String[] words) {
        for (int i = 0; i < words.length; i++) {
            map.put(words[i], i);
        }
    }
    
    //find max-length string index
    public int f(String prefix, String suffix) {
        if (prefix == null || suffix == null) return -1;
        int maxLen = Math.max(prefix.length(), suffix.length());
        String resStr = "";
        int resIndex = -1;
        for (Map.Entry entry: map.entrySet()) {
            String cur = entry.getKey();
            int curLen = cur.length();
            if (curLen < maxLen) continue;
            if (cur.startsWith(prefix) && cur.substring(curLen-suffix.length()).equals(suffix)) {
                if (entry.getValue() > resIndex) {
                    resStr = entry.getKey();
                    resIndex = entry.getValue();
                }
            }
        }
        return resIndex;
    }
}

Solution (Trie)