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:

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 words;
        
        int leftIdx  = 0;
        int rightIdx = 0;
        
        while (rightIdx < str.size()) 
        {
            while (rightIdx < str.size() && str[rightIdx] != ' ')
                rightIdx++;
                
            words.push_back(str.substr(leftIdx, rightIdx-leftIdx));
            
            leftIdx  = rightIdx+1;
            rightIdx = rightIdx+1;
        }
        
        if (pattern.size() != words.size())
            return false;
        
        map matchTable;
        map reverseTable;
        
        for (int i=0; i