Description
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 <= 501 <= pattern.length = words[i].length <= 20
Solutions
找到所有与 pattern 形式相同的字符串保存下来。
1. Greedy + Dict
理解题意就可以了，不是很难，但是写出来的代码就不够优雅，一堆 if。用字典存映射关系，然后挨个字符去找对应！
找对应的时候注意，如果字符串的字符不在字典中，还要判断是不是在已经存进字典的 values 中。
# Time: O(n^2)
# Space: O(n)
class Solution:
def findAndReplacePattern(self, words: List[str], pattern: str) -> List[str]:
res = []
n = len(pattern)
for item in words:
dic = {}
Flag = True
for i in range(n):
if pattern[i] in dic:
if item[i] != dic[pattern[i]]:
Flag = False
break
else:
if item[i] in dic.values():
Flag = False
break
dic[pattern[i]] = item[i]
if Flag:
res.append(item)
return res
# 46/46 cases passed (32 ms)
# Your runtime beats 79 % of python3 submissions
# Your memory usage beats 100 % of python3 submissions (12.7 MB)