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:
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.

Credits:
Special thanks to @minglotus6 for adding this problem and creating all test cases

把字符数组和字符串数组，映射到‘a’~'z'然后 判断两个映射后的字符串是否相等就行

class Solution {
public:
    bool wordPattern(string pattern, string str) {
        map<string, char> mp;
        string t = "";
        int k = 0;
        string ans = "";
        for (int i = 0; i < str.size(); ++i) {
            if (str[i] == ' ') {
                if (!mp[t]) {
                    mp[t] = char(k + 'a');
                    ++k;
                }
                ans += mp[t];
                t = "";
            }
            else t += str[i];
        }
        if (t.size()) {
            if (mp[t]) ans += mp[t];
            else mp[t] = char(k + 'a'), ans += mp[t];
        }
        map<char, char> mp2;
        string w = "";
        k = 0;
        for (int i = 0; i < pattern.size(); ++i) {
            if (!mp2[pattern[i]]) {
                mp2[pattern[i]] = char(k + 'a');
                ++k;
            }
            w += mp2[pattern[i]];
        }
        return ans == w;
    }
};