题目：
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:
"abba", str = "dog cat cat dog" should return true."abba", str = "dog cat cat fish" should return false."aaaa", str = "dog cat cat dog" should return false."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.
思路：考察的是字符串模式匹配，可以用map来解决，先将str分割放到一个vector<string>中，再将pattern分割一起放入map<char,string>中，遍历判断是否是对应的键或值即可。
代码：
class Solution { public: bool wordPattern(string pattern, string str) { stringstream ss(str); string s; vector<string> strVec; while(ss >> s) { strVec.push_back(s); } if(strVec.size() != pattern.size()) return false; map<char, string> hash; int i = 0; for(auto c : pattern) { if(hash.count(c)) { if(hash[c] != strVec[i]) return false; } else { for(auto p : hash) { if(p.second == strVec[i]) return false; } hash[c] = strVec[i]; } ++i; } return true; } };
原文：http://www.cnblogs.com/zhangbaochong/p/5188201.html