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.

判断字符串是否是模式串的形式。

对字符串进行分词，用map保存和模式串字符的对应关系

class Solution {public:    bool wordPattern(string pattern, string str) {        str += " ";        int j = 0;        unordered_map<string, string> mp;        for(int i = 0; i < str.size(); i++)        {            int pos = str.find(" ", i);            string tmp = str.substr(i, pos - i);            i = pos;            if(j == pattern.size()) return false;            string key(pattern[j] + "\0");            if(mp.find(key) == mp.end())            {                if(mp.find(tmp) == mp.end())                 {                    mp[tmp] = key;                    mp[key] = tmp;                }                else return false;            }            else if(mp[key] != tmp) return false;            j++;        }        if(j != pattern.size()) return false;        return true;    }};