leetcode：290. 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.

/** * @param {string} pattern * @param {string} str * @return {boolean} */var wordPattern = function(pattern, str) {    var wordMap = {};    var letterMap = {};    var strArr = str.split(' ');    if(strArr.length !== pattern.length) return false;    for(var i = 0; i <pattern.length; i++) {        if (typeof(wordMap[strArr[i]]) == "undefined") {             wordMap[strArr[i]] = pattern[i];        } else if(wordMap[strArr[i]] !== pattern[i]) {            return false;        }          if (typeof(letterMap[pattern[i]]) == "undefined") {             letterMap[pattern[i]] = strArr[i];        } else if(letterMap[pattern[i]] !== strArr[i]) {            return false;        }      }    return true;};