290. 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.

public class Solution {    public boolean wordPattern(String pattern, String str) {        String[] words = str.split(" ");        if (words.length != pattern.length()) return false;        HashMap<Character, String> map = new HashMap<Character, String>();        for (int i = 0; i < pattern.length(); i++) {            char c = pattern.charAt(i);            String s = words[i];            if (map.containsKey(c)) {                if (!map.get(c).equals(words[i])) return false;            } else {                if (map.containsValue(words[i])) return false;                map.put(c, words[i]);            }        }        return true;    }}