Word Pattern

Source

• leetcode: 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.

Java

public class Solution {
    public boolean wordPattern(String pattern, String str){
        HashMap<Character, String> map1 = new HashMap<Character, String>();
        HashMap<String, Character> map2 = new HashMap<String, Character>();
        String[] strs = str.split("\\s");
        if(pattern.length()!=strs.length) return false;

        for(int i=0; i<pattern.length(); i++){
            char c = pattern.charAt(i);
            if(!map1.containsKey(c)){
                if(map2.containsKey(strs[i])){
                    return false;
                }
                else{
                    map1.put(c, strs[i]);
                    map2.put(strs[i], c);
                }
            }
            else if(!map1.get(c).equals(strs[i])){
                return false;
            }
        }
        return true;
    }
}

Python

class Solution(object):
    def wordPattern(self, pattern, str):
        """
        :type pattern: str
        :type str: str
        :rtype: bool
        """
        pat_to_str = {}
        str_to_pat = {}

        str = str.split();

        if len(pattern)!=len(str):
            return False;

        for i in range(len(pattern)):
            pat = pattern[i]
            s = str[i]
            if not pat in pat_to_str:
                if s in str_to_pat:
                    return False
                else:
                    pat_to_str[pat]=s
                    str_to_pat[s]=pat
            elif pat_to_str[pat]!=s:
                return False

        return True