(LeetCode)Word Pattern --- 模式匹配

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.

Credits:

Special thanks to @minglotus6 for adding this problem and creating all test cases.

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解题分析：

题目的意思是给出一个字符串 str, 再给出一个模式 pattern，然后要求就是判断给出的字符串是否和给出的模式相匹配，

匹配的话就返回True, 否则返回False.

思路一：

利用hash思想将pattern做索引，str为值存储，与str为索引，pattern为值进行匹配。

# -*- coding:utf-8 -*-
__author__ = 'jiuzhang'
class Solution(object):
    def wordPattern(self, pattern, str):
        words = str.split()
        if len(pattern) != len(words):
            return False
        ptnDict, wordDict = {}, {}
        for ptn, word in zip(pattern, words):
            if ptn not in ptnDict:
                ptnDict[ptn] = word
            if word not in wordDict:
                wordDict[word] = ptn
            if wordDict[word] != ptn or ptnDict[ptn] != word:
                return False
        return True

思路二：

利用位置进行匹配。

使用 index 以及，map,find 函数。

# -*- coding:utf-8 -*-
__author__ = 'jiuzhang'
class Solution(object):
    def wordPattern(self, pattern, str):
        s = pattern
        t = str.split()
        return map(s.find, s) == map(t.index, t)