_290.java

package com.fishercoder.solutions;

import java.util.HashMap;
import java.util.Map;

/**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 _290 {

    public boolean wordPattern(String pattern, String str) {
        String[] words = str.split(" ");
        char[] patterns = pattern.toCharArray();
        Map<Character, String> map = new HashMap();
        if(patterns.length != words.length) return false;
        for(int i = 0; i < patterns.length; i++){
            if(map.containsKey(patterns[i])){
                if(!map.get(patterns[i]).equals(words[i])) return false;
            } else {
                if(map.containsValue(words[i])) return false;//this is for this case: "abba", "dog dog dog dog"
                map.put(patterns[i], words[i]);
            }
        }
        return true;
    }

}