leetcode 290: Word Pattern

Word Pattern

Total Accepted:
1733 Total Submissions:
6204 Difficulty: Easy

Given a

pattern

and a string

str

, find if

str

follows the same pattern.

Examples:

pattern =

"abba"

, str =

"dog cat cat dog"

should return true.
pattern =

"abba"

, str =

"dog cat cat fish"

should return false.
pattern =

"aaaa"

, str =

"dog cat cat dog"

should return false.
pattern =

"abba"

, str =

"dog dog dog dog"

should return false.

Notes:

Both

pattern

and

str

contains only lowercase alphabetical letters.
Both

pattern

and

str

do not have leading or trailing spaces.
Each word in

str

is separated by a single space.
Each letter in

pattern

must map to a word with length that is at least 1.

Credits:

Special thanks to
@minglotus6 for adding this problem and creating all test cases.

[思路]
char 和 string 一一对应. 建一个map. 同时set里面保存string, 避免重复, 出现多对1的情况.

[CODE]

public class Solution {
public boolean wordPattern(String pattern, String str) {
//input check

String[] strs = str.split(" ");
if(pattern.length() != strs.length  ) return false;

Map<Character, String> map = new HashMap<>();
Set<String> unique = new HashSet<>();

for(int i=0; i<pattern.length(); i++) {
char c = pattern.charAt(i);
if(map.containsKey(c) ) {
if(!map.get(c).equals(strs[i])) return false;
} else {
if(unique.contains(strs[i])) return false;
map.put(c, strs[i]);
unique.add(strs[i]);
}
}
return true;
}
}