> For the complete documentation index, see [llms.txt](https://bhabs.gitbook.io/prepbook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bhabs.gitbook.io/prepbook/coding/word-pattern.md).

# 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:**

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.

```
class Solution(object):
    def wordPattern(self, pattern, str):
        """
        :type pattern: str
        :type str: str
        :rtype: bool
        """
        if not pattern and not str:
            return True

        # since str has words separated by spaces    
        str_arr = str.split()
        if len(str_arr) != len(pattern):
            return False

        dict = {}
        start = 0
        for idx in xrange(len(pattern)):
            ch = pattern[idx]
            substr = ''
            #/////////////////////////////////////////
            # easy to obtain substr when the str has ' ' (space) separating words
            #/////////////////////////////////////////
            for idx2 in xrange(start, len(str)):
                if str[idx2] != ' ':
                    substr += str[idx2]
                else:
                    start = idx2 + 1
                    break;

            #print 'ch: ', ch, ' substr: ', substr, ' start: ', start
            if ch not in dict:
                if substr not in dict.values():
                    #print 'hashing: ', ch, ' -> ', substr
                    dict[ch] = substr
                else:
                    return False

            else:
                if dict[ch] != substr:
                    return False

        return True
```


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