Formatted question description: https://leetcode.ca/all/890.html

# 890. Find and Replace Pattern (Medium)

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

Companies:

Related Topics:
String

## Solution 1.

// OJ: https://leetcode.com/problems/find-and-replace-pattern/

// Time: O(CW) where C is count of words and W is word length
// Space: O(W)
class Solution {
private:
bool match(string &word, string &pattern) {
unordered_map<char, char> m;
unordered_set<char> used;
for (int i = 0; i < word.size(); ++i) {
if (m.find(word[i]) == m.end()) {
if (used.find(pattern[i]) != used.end()) return false;
m[word[i]] = pattern[i];
used.insert(pattern[i]);
} else if (m[word[i]] != pattern[i]) return false;
}
return true;
}
public:
vector<string> findAndReplacePattern(vector<string>& words, string pattern) {
vector<string> ans;
for (auto word : words) {
if (match(word, pattern)) ans.push_back(word);
}
return ans;
}
};


Java

class Solution {
public List<String> findAndReplacePattern(String[] words, String pattern) {
List<String> matchWords = new ArrayList<String>();
for (String word : words) {
if (matchPattern(word, pattern))
}
return matchWords;
}

public boolean matchPattern(String word, String pattern) {
if (word.length() != pattern.length())
return false;
Map<Character, Character> map1 = new HashMap<Character, Character>();
Map<Character, Character> map2 = new HashMap<Character, Character>();
int length = word.length();
for (int i = 0; i < length; i++) {
char c1 = word.charAt(i), c2 = pattern.charAt(i);
if (map1.containsKey(c1)) {
if (map1.get(c1) != c2)
return false;
} else
map1.put(c1, c2);
if (map2.containsKey(c2)) {
if (map2.get(c2) != c1)
return false;
} else
map2.put(c2, c1);
}
return true;
}
}