LeetCode in TypeScript

290. Word Pattern

Easy

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

Example 4:

Input: pattern = “abba”, s = “dog dog dog dog”

Output: false

Constraints:

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

Solution

function wordPattern(pattern: string, s: string): boolean {
    const map = new Map<string, string>()
    const words = s.split(' ')
    if (words.length !== pattern.length) {
        return false
    }
    for (let i = 0; i < pattern.length; i++) {
        const char = pattern[i]
        const word = words[i]
        if (!map.has(char)) {
            if ([...map.values()].includes(word)) {
                return false
            }
            map.set(char, word)
        } else {
            if (map.get(char) !== word) {
                return false
            }
        }
    }
    return true
}

export { wordPattern }

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