(java)Word Pattern

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.

思路:本题就是实时维护一个数据字典，现有字典里如果有pattern中对应的元素，则判断str中对应位置的子串是否与字典中的一样，如果没有，则将此匹配规则加入到字典中。

注意:在字典中的索引项没有pattern中对应的位置的字母时，还要判断此字母在str中对应的子串是否在字典有含有

代码如下(已通过leetcode)

public class Solution {

public boolean wordPattern(String pattern, String str) {

String[] strs=str.split(" ");

if(pattern.length()!=strs.length) return false;

String temp="";

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

for(int i=0;i<strs.length;i++) {

if(map.containsKey(pattern.charAt(i)))

{

if(map.get(pattern.charAt(i)).equals(strs[i])) temp+=strs[i];

else return false;

}

else {

if(map.containsValue(strs[i])) return false;

else {

map.put(pattern.charAt(i), strs[i]);

temp+=strs[i];

}

}

temp+=" ";

}

temp=temp.substring(0, temp.length()-1);

System.out.println(temp);

if(str.equals(temp)) return true;

else return false;

}

}