leetcode290

1、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) {
        istringstream strcin(str);
        string s;
        vector<string> vs;
        while(strcin >> s) vs.push_back(s);
        if (pattern.size() != vs.size()) return false;
        map<string, char> s2c;
        map<char, string> c2s;
        for (int i = 0; i < vs.size(); ++i) {
            if (s2c[vs[i]] == 0 && c2s[pattern[i]] == "") { 
                s2c[vs[i]] = pattern[i]; 
                c2s[pattern[i]] = vs[i]; 
                continue; 
            }
            if (s2c[vs[i]] != pattern[i]) return false;
        }
        return true;
    }
};

1、C++引入了ostringstream、istringstream、stringstream这三个类，要使用他们创建对象就必须包含这个头文件。
istringstream类用于执行C++风格的串流的输入操作。
ostringstream类用于执行C风格的串流的输出操作。
strstream类同时可以支持C风格的串流的输入输出操作。

istringstream的构造函数原形如下：
istringstream::istringstream(string str);
它的作用是从string对象str中读取字符。
举个栗子～

#include  
#include        //istringstream 必须包含这个头文件
#include  
using namespace std;  
int main()  
{  
    string str="i an a boy";  
    istringstream is(str);  
    string s;  
    while(is>>s)  
    {  
        cout<

2、主要思路就是把需要匹配的字符串一块块的存到map里，如果匹配最终的效果就是一块字符串对应一个字符，而如果完全匹配，则map中对应的字符和pattern中对应的一样～