java 290.单词模式（#two HashMap）.java

Posted 2021-05-08

public boolean wordPattern(String pattern, String str) {
    String[] words = str.split(" ");
    if (words.length != pattern.length())
        return false;
    Map index = new HashMap();
    for (Integer i=0; i<words.length; ++i)
        if (index.put(pattern.charAt(i), i) != index.put(words[i], i))
            return false;
    return true;
}

/*
Put Method Returns:
the previous value associated with key, or null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key.)*/

public class Solution {
    public boolean wordPattern(String pattern, String str) {
        if(pattern == null || pattern.length() == 0) return false;
        if(str == null || str.length() == 0) return false;
        String[] arr = str.split(" ");
        if(pattern.length() != arr.length) {
            return false;
        } 
       
        HashMap<Character, String> map = new HashMap<>();
        for(int i =0; i < pattern.length(); i ++) {
            char ch = pattern.charAt(i);
            String temp = arr[i];
            if(map.containsKey(ch)) {
                if(!map.get(ch).equals(temp)) {
                    return false;
                }
            } else {
                map.put(ch, temp);
            }
        }
        HashSet<String> vals = new HashSet<>();
        vals.addAll(map.values());
        return vals.size() == map.values().size();
    }
}

public class Solution {
    public boolean wordPattern(String pattern, String str) {
        String[] strs = str.split(" ");
        if (strs.length != pattern.length()) return false;
        Map<Character, String> map1 = new HashMap<>();
        Map<String, Character> map2 = new HashMap<>();
        for(int i = 0; i < pattern.length(); i++) {
            char p = pattern.charAt(i);
            String s = strs[i];
            if ((map1.containsKey(p) && !map1.get(p).equals(s)) || (map2.containsKey(s) && map2.get(s) != p)) {
                return false;
            }
            map1.put(p,s);
            map2.put(s,p);
        }
        return true;
    }
}