LeetCode 290. Word Pattern

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class Solution {
    public boolean wordPattern(String pattern, String str) {
        Map<String, Character> str2ch = new HashMap<>();
        Map<Character, String> ch2str = new HashMap<>();
        int n = str.length();
        int i = 0;
        for (char ch : pattern.toCharArray()) {
            if (i >= n) return false;
            int j = i;
            while (j < n && str.charAt(j) != ' ') j++;
            String tmp = str.substring(i, j);
            if (str2ch.containsKey(tmp) && str2ch.get(tmp) != ch) return false;
            if (ch2str.containsKey(ch) && !tmp.equals(ch2str.get(ch))) return false;
            str2ch.put(tmp, ch);
            ch2str.put(ch, tmp);
            i = j + 1;
        }
        return i >= n;
    }
}
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class Solution {
public:
    bool wordPattern(string pattern, string str) {
        unordered_map<char, int> p2i;
        unordered_map<string, int> w2i;
        istringstream in(str);
        int i = 0, n = pattern.size();
        for (string word; in >> word; ++i) {
            if (i == n || p2i[pattern[i]] != w2i[word])
                return false;
            p2i[pattern[i]] = w2i[word] = i + 1;
        }
        return i == n;
    }
};
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class Solution:
    def wordPattern(self, pattern: str, s: str) -> bool:
        word2ch = dict()
        ch2word = dict()
        words = s.split()
        if len(pattern) != len(words): return False
        for ch, word in zip(pattern, words):
            if (word in word2ch and word2ch[word] != ch) or (ch in ch2word and ch2word[ch] != word):
                return False
            word2ch[word] = ch
            ch2word[ch] = word
        return True