LeetCode题解：Word Pattern

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:
pattern = “abba”, str = “dog cat cat dog” should return true.
pattern = “abba”, str = “dog cat cat fish” should return false.
pattern = “aaaa”, str = “dog cat cat dog” should return false.
pattern = “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.

题意：给定一个字符串表示字符串的模式，以及一个输入字符串，判断输入字符串是否满足该模式

解题思路：建立模式字符和字符串单词的匹配，第一反应是用单词作键，模式字符为值，考虑到字符和单词对比需要转换，就用单词的索引来映射了。因为满足匹配关系的话，对应的索引关系是一样的。

代码：

public class Solution {
    public boolean wordPattern(String pattern, String str) {
        String[] words = str.split(" ");
        if (words.length != pattern.length())
            return false;
        Map index = new HashMap();
        for (Integer i=0; iif (index.put(words[i], pattern.charAt(i)) != null && index.put(words[i], pattern.charAt(i)) != pattern.charAt(i))
                return false;
        return true;
    }
}