LeetCode 290. 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

Constraints:

• 1 <= pattern.length <= 300
• pattern contains only lower-case English letters.
• 1 <= s.length <= 3000
• s contains only lowercase English letters and spaces ' '.
• s does not contain any leading or trailing spaces.
• All the words in s are separated by a single space.

---

和昨天做的205 Ismorphic String（http://t.csdn.cn/LzVxH）几乎是一样的，只是前面多加了个split string by space。熟练地采用昨天我觉得最好的那个map + set的方法做完了。

class Solution {
    public boolean wordPattern(String pattern, String s) {
        Map<String, Character> map = new HashMap<>();
        Set<Character> used = new HashSet<>();
        String[] splited = s.split(" ");
        if (splited.length != pattern.length()) {
            return false;
        }
        for (int i = 0; i < splited.length; i++) {
            char c = pattern.charAt(i);
            if (map.containsKey(splited[i])) {
                if (c != map.get(splited[i])) {
                    return false;
                }
            } else {
                if (used.contains(c)) {
                    return false;
                }
                used.add(c);
                map.put(splited[i], c);
            }
        }
        return true;
    }
}