Leetcode: Find and Replace Pattern

Find and Replace Pattern



Similar Problems:


You have a list of words and a pattern, and you want to know which words in words matches the pattern.

A word matches the pattern if there exists a permutation of letters p so that after replacing every letter x in the pattern with p(x), we get the desired word.

(Recall that a permutation of letters is a bijection from letters to letters: every letter maps to another letter, and no two letters map to the same letter.)

Return a list of the words in words that match the given pattern.

You may return the answer in any order.

Example 1:

Input: words = ["abc","deq","mee","aqq","dkd","ccc"], pattern = "abb"
Output: ["mee","aqq"]
Explanation: "mee" matches the pattern because there is a permutation {a -> m, b -> e, ...}. 
"ccc" does not match the pattern because {a -> c, b -> c, ...} is not a permutation,
since a and b map to the same letter.

Note:

  • 1 <= words.length <= 50
  • 1 <= pattern.length = words[i].length <= 20

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.


  • Solution:
// Blog link: https://code.dennyzhang.com/find-and-replace-pattern
// Basic Ideas: hashmap
// Complexity: Time O(n), Space O(1)
func encodeString(word string) string {
    m := map[rune]int{}
    i, s := 0, ""
    for _, ch := range word {
        _, ok := m[ch]
        if !ok {
            m[ch] = i
            i++
        }
        s += string('a'+byte(m[ch]))
    }
    return s
}

func findAndReplacePattern(words []string, pattern string) []string {
    p := encodeString(pattern)
    res := []string{}
    for _, word := range words {
        if encodeString(word) == p {
            res = append(res, word)
        }
    }
    return res
}
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