Word Pattern(leetcode290)

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.

Example 1:

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

Example 2:

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

Example 3:

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

Example 4:

Input: pattern = , str = 
Output: false"abba""dog dog dog dog"

Notes:
You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.

//對於匹配的問題 感受通常用map都是能夠的
public static boolean wordPattern(String pattern, String str) {
    boolean result = true;
    Map<Character, String> map = new HashMap<>();
    String arrays[] = str.split(" ");
    if(arrays.length != pattern.length()){
        return false;
    }
    for (int i = 0; i < pattern.length(); i++) {
        if (map.containsKey(pattern.charAt(i))) {
            String value = map.get(pattern.charAt(i));
            if (!value.equals(arrays[i])) {
                result = false;
                break;
            }
        } else {
            if(map.containsValue(arrays[i])) {
                return false;
            }
            map.put(pattern.charAt(i), arrays[i]);

        }

    }

    return result;
}

 

//化簡一下 直接經過put操做判斷 簡化了contains操做
public static boolean wordPattern2(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;
}

git:https://github.com/woshiyexinjie/leetcode-xin