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.

Solution:

public class Solution {
    public boolean wordPattern(String pattern, String str) {
        char[] p = pattern.toCharArray();
        String[] s = str.split("\\s+");
        Map<Character, String> p2s = new HashMap<>();
        Map<String, Character> s2p = new HashMap<>();
        if(p.length!=s.length) return false;
        for(int i=0; i<p.length; i++){
            if(!p2s.containsKey(p[i]) && !s2p.containsKey(s[i])){
                p2s.put(p[i], s[i]);
                s2p.put(s[i], p[i]);
            } else if(p2s.containsKey(p[i]) && s2p.containsKey(s[i])){
                if(!p2s.get(p[i]).equals(s[i])) return false;
            } else {
                return false;
            }
        }
        return true;
    }
}