890. Find and Replace Pattern

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.



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

Rust Solution

struct Solution;
use std::collections::HashMap;

trait Matches {
    fn matches(&self, pattern: &[char], n: usize) -> bool;

impl Matches for Vec<char> {
    fn matches(&self, pattern: &[char], n: usize) -> bool {
        if self.len() != n {
            return false;
        let mut hm1: HashMap<char, char> = HashMap::new();
        let mut hm2: HashMap<char, char> = HashMap::new();
        for i in 0..n {
            let c1 = self[i];
            let c2 = pattern[i];
            if let Some(old) = hm1.insert(c1, c2) {
                if old != c2 {
                    return false;
            if let Some(old) = hm2.insert(c2, c1) {
                if old != c1 {
                    return false;

impl Solution {
    fn find_and_replace_pattern(words: Vec<String>, pattern: String) -> Vec<String> {
        let n = pattern.len();
        let pattern: Vec<char> = pattern.chars().collect();
        let mut res = vec![];
        for word in words {
            let word: Vec<char> = word.chars().collect();
            if word.matches(&pattern, n) {

fn test() {
    let words = vec_string!["abc", "deq", "mee", "aqq", "dkd", "ccc"];
    let pattern = "abb".to_string();
    let res = vec_string!["mee", "aqq"];
    assert_eq!(Solution::find_and_replace_pattern(words, pattern), res);

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