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.

思路：使用两个map词典来进行比较。

class Solution {public:    bool wordPattern(string pattern, string str) {        map<char,int> p2i;        map<string,int> w2i;        istringstream in(str);        int i=0,n=pattern.size();        for(string word;in>>word;++i){            if(i==n||p2i[pattern[i]]!=w2i[word])            return false;            p2i[pattern[i]]=w2i[word]=i+1;        }        return i==n;    }};