【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.

class Solution {public:    bool wordPattern(string pattern, string str) {        vector<string>vc;        map<char,string>m1;        map<string,char>m2;        if(pattern.length()==0 && str.length()!=0) return false;        if(pattern.length()!=0 && str.length()==0) return false;        int len1 = pattern.size();        int len2 = str.size();        string word;        for(int i =0; i < len2; i++)        {            if(str[i] != ' ')             word += str[i];            else            {                vc.push_back(word);                word = "";            }            if(i==len2-1)             vc.push_back(word);        }        if(vc.size() != len1) return false;         for(int j =0; j <len1; j++)        {            map<char,string>::iterator it1;            map<string, char>::iterator it2;            it1 = m1.find(pattern[j]);            it2 = m2.find(vc[j]);            if(it1==m1.end() && it2==m2.end())            {                m1[pattern[j]] = vc[j];                m2[vc[j]] = pattern[j];            }            else if(it1!=m1.end() && it2!=m2.end())            {                if(m1[pattern[j]] != vc[j] || m2[vc[j]]!= pattern[j])                 return false;            }            else return false;        }       return true;    }};