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Given a pattern and a string str, find if str follows the same pattern.
Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in str.
Examples:
"abba", str = "dog cat cat dog" should return true."abba", str = "dog cat cat fish" should return false."aaaa", str = "dog cat cat dog" should return false."abba", str = "dog dog dog dog" should return false.
Notes:
You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.
Credits:
Special thanks to @minglotus6 for adding this problem and creating all test cases.
Solution:
public class Solution { public boolean wordPattern(String pattern, String str) { if (str.isEmpty() && pattern.isEmpty()) return true; if (str.isEmpty() || pattern.isEmpty()) return false; String[] map = new String[26]; Arrays.fill(map,""); String[] words = str.split(" "); HashSet<String> assigned = new HashSet<String>(); if (pattern.length()!=words.length) return false; for (int i=0;i<pattern.length();i++){ char code = pattern.charAt(i); if (!map[code-‘a‘].isEmpty()){ // code.word != word, it is wrong if (!map[code-‘a‘].equals(words[i])){ return false; } } else { // code.word is empty but word has been assigned to another code, it is wrong. if (assigned.contains(words[i])){ return false; } assigned.add(words[i]); map[code-‘a‘] = words[i]; } } return true; } }
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原文地址：http://www.cnblogs.com/lishiblog/p/5836153.html
