# [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<String, Integer> 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<String, Integer> 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;
}
}``````

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