标签：ret i++ begin public lte support bsp search gen
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
分析：因为要找出word一定begin with prefix，以及end with suffix，有点麻烦。其实找begin with prefix不麻烦，麻烦的是怎么找end with suffix. 这里有点巧的方法是对于每个word，把它所有的suffx_word
放在trie里，比如apple, 我们就把 "_apple", "e_apple", "le_apple", "ple_apple", "pple_apple", "apple_apple" 都存在trie里。这样可以用trie把所有的情况都包括了。
1 public class WordFilter { 2 private TrieNode root = new TrieNode(‘ ‘, -1); 3 public WordFilter(String[] words) { 4 for (int weight = 0; weight < words.length; weight++) { 5 List<String> suffixList = generateSuffixList(words[weight]); 6 for (String word : suffixList) { 7 addWord(word, weight); 8 } 9 } 10 } 11 12 public void addWord(String word, int weight) { 13 TrieNode current = root; 14 for (int i = 0; i < word.length(); i++) { 15 char ch = word.charAt(i); 16 TrieNode node = current.getChildNode(ch); 17 if (node == null) { 18 current.map.put(ch, new TrieNode(ch, weight)); 19 node = current.getChildNode(ch); 20 } 21 node.weight = Math.max(weight, node.weight); 22 current = node; 23 } 24 } 25 26 private List<String> generateSuffixList(String word) { 27 List<String> suffixList = new ArrayList<>(); 28 int length = word.length(); 29 for (int i = length; i >= 0; i--) { 30 String sub = word.substring(i, length); 31 suffixList.add(sub + "_" + word); 32 } 33 return suffixList; 34 } 35 36 public int f(String prefix, String suffix) { 37 if (root == null) return -1; 38 TrieNode current = root; 39 String word = suffix + "_" + prefix; 40 for (char ch : word.toCharArray()) { 41 current = current.getChildNode(ch); 42 if (current == null) { 43 return -1; 44 } 45 } 46 return current.weight; 47 } 48 }
标签：ret i++ begin public lte support bsp search gen
原文地址：https://www.cnblogs.com/beiyeqingteng/p/11254893.html
