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;
}
}