LeetCode ： 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:
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

class Solution {  public:    bool wordPattern(string pattern, string str) {      unordered_map<char,string> map;      unordered_map<string,char> map2;      vector<string> vec;      int j=0;      for(int i=0;i<str.size();i++){          if(str[i]==' '){              string tmp =str.substr(j,i-j);              vec.push_back(tmp);              j=i+1;          }          if(i==str.size()-1){              string tmp =str.substr(j,i-j+1);              vec.push_back(tmp);          }      }      if(pattern.size()!=vec.size())return false;      for(int i=0;i<pattern.size();i++){          if(map.find(pattern[i])==map.end()&&map2.find(vec[i])==map2.end()){              map.insert(make_pair(pattern[i],vec[i]));              map2.insert(make_pair(vec[i],pattern[i]));          }          else if(map[pattern[i]]!=vec[i]||map2[vec[i]]!=pattern[i])return false;      }      return true;  }  };