[Leetcode] Word Pattern

描述

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.

分析

这道题与之前出现过的 Isomorphic Strings 基本一样，只不过是将字符变成了字符串，思路还是一样，直接看代码。

代码

class Solution {public:    bool wordPattern(string pattern, string str) {        unordered_map<char,int> m1;        unordered_map<string,int> m2;        istringstream in(str);        int i = 0;        for (string word; in >> word; i++) {            if (m1.find(pattern[i]) != m1.end() || m2.find(word) != m2.end()){                if (m1[pattern[i]] != m2[word]) return false;            } else {                m1[pattern[i]] = m2[word] = i + 1;            }        }        return i == pattern.size();    }};