290. Word Pattern

Posted 2020-10-11 andywu

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:

1. pattern = "abba", str = "dog cat cat dog" should return true.
2. pattern = "abba", str = "dog cat cat fish" should return false.
3. pattern = "aaaa", str = "dog cat cat dog" should return false.
4. 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.

题目含义：给定一个模式，判断句子中的单词是否满足模式？

 

 1     public boolean wordPattern(String pattern, String str) {
 2         if(str.split(" ").length != pattern.length()) return false;
 3         Map<Character,String> map = new HashMap<>(pattern.length());//维护pattern字符与后面字符串的映射关系
 4         Map<String,Boolean> valueMap = new HashMap<>();
 5         
 6         char p_arra[] = pattern.toCharArray();
 7         String str_arra[] = str.split(" ");
 8         int index=0;
 9         while (index<p_arra.length)
10         {
11             if (!map.containsKey(p_arra[index]))
12             {
13                 if (valueMap.containsKey(str_arra[index])) return false;
14                 map.put(p_arra[index],str_arra[index]);
15                 valueMap.put(str_arra[index],true);
16             }else if (!map.get(p_arra[index]).equals(str_arra[index])) return false;
17             index++;
18         }
19         return true;        
20     }