Java [Leetcode 290]Word Pattern
题目描述:
Given a pattern
and a string str
, find if str
follows the same pattern.
Here follow means a full match, such that there is a bijection between a letter in pattern
and a non-empty word in str
.
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:
You may assume pattern
contains only lowercase letters, and str
contains lowercase letters separated by a single space.
解题思路:
使用HashMap来做。
代码如下:
public class Solution { public boolean wordPattern(String pattern, String str) { if(pattern == null || str == null) return false; String[] words = str.split(" "); if(pattern.length() != words.length) return false; Map<Character, String> map = new HashMap<Character, String>(); for(int i = 0; i < pattern.length(); i++){ char t = pattern.charAt(i); if(map.containsKey(t)){ if(!words[i].equals(map.get(t))) return false; } else { if(map.containsValue(words[i])) return false; map.put(t, words[i]); } } return true; } }