500. Keyboard Row

题目描述：

Given a List of words, return the words that can be typed using letters of alphabet on only one row's of American keyboard like the image below.

Example 1:

Input: ["Hello", "Alaska", "Dad", "Peace"]
Output: ["Alaska", "Dad"]

Note:

1. You may use one character in the keyboard more than once.
2. You may assume the input string will only contain letters of alphabet.

解题思路：

判断输入的每个单词中的字母是否都在键盘的同一行上。

代码：

class Solution {
public:
    vector<string> findWords(vector<string>& words) {
        vector<string> ret;
        for (auto word : words) {
            bool sig = true;
            char c = tolower(word[0]);
            int num = alpha[c];
            for (int i = 1; i < word.size(); ++i) {
                c = tolower(word[i]);
                if (alpha[c] != num) {
                    sig = false;
                    break;
                }
            }
            if (sig)
                ret.push_back(word);
        }
        return ret;
    }
    
    unordered_map<char, int> alpha = {
        {'q', 1}, {'w', 1}, {'e', 1}, {'r', 1}, {'t', 1}, {'y', 1}, {'u', 1}, {'i', 1}, {'o', 1}, {'p', 1},
        {'a', 2}, {'s', 2}, {'d', 2}, {'f', 2}, {'g', 2}, {'h', 2}, {'j', 2}, {'k', 2}, {'l', 2},
        {'z', 3}, {'x', 3}, {'c', 3}, {'v', 3}, {'b', 3}, {'n', 3}, {'m' ,3}
    };
};