Word Pattern

https://leetcode.com/problems/word-pattern/

Given a pattern and a string s, find if s 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 s.

Example 1:

Input: pattern = "abba", s = "dog cat cat dog"
Output: true

Example 2:

Input: pattern = "abba", s = "dog cat cat fish"
Output: false

Example 3:

Input: pattern = "aaaa", s = "dog cat cat dog"
Output: false

Solution:

Ok, ok, looks like that is an easy problem. Right?

But a want to add some additional cases:

aabba
bbaac

And return will be false. is it clear?

We should have links between both sides, like a to b and b to a, because it is possible to have an opposite case.

That is why we have to prepare two dictionaries and fill them. And if we successfully iterate over the word/sentence, that is it. =)

  public boolean wordPattern(String pattern, String s) {
    String[] words = s.split(" ");
    Map<Character, String> mapPat = new HashMap<>();
    Map<String, Character> sMap = new HashMap<>();
     
     
    if (pattern.length() != words.length){
      return false;
    }
     
    for(int i = 0; i < words.length; i++){
      char curChar = pattern.charAt(i);
      String curWord = words[i];
      if (mapPat.containsKey(curChar)){
        if(!mapPat.get(curChar).equals(curWord)){
          return false;
        }
      } else if (sMap.containsKey(curWord)){
        if(!sMap.get(curWord).equals(curChar)){
          return false;
        }
      }
       
      else {
        mapPat.put(curChar, curWord); 
        sMap.put(curWord, curChar);
      }
    }
    return true;
  }