leetcode 500. Keyboard Row(easy)-优快云博客

本文介绍了一种使用C++实现的算法，该算法能够从给定的单词列表中筛选出那些仅使用美国键盘某一排字母即可拼写的单词。通过构建一个映射表来标记每个大写字母所在的键盘行数，进而判断单词是否符合要求。

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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.

American keyboard

Example 1:

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

Note:

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

题目的要求是找出在键盘一行可以输出的单词，那么采用空间换时间的方法，以每个大写字母为key，层数为值存放键盘信息。这里用了map结构。

class Solution {
public:
    
     bool isOneRow(string s,map<char,int> &temp)
     {
         int len = s.length();
         int flag = 0;
         for(int i = 0;i<len;i++)
         {
             if(i == 0)
                 flag = temp[toupper(s[i])];
             else
             {
                 int m = temp[toupper(s[i])];
                 if(flag != m)
                    return false;
             
             }
         }
         return true;
     }
    vector<string> findWords(vector<string>& words) {
         map<char,int> temp;
         temp['A'] = 2;
         temp['S'] = 2;
         temp['D'] = 2;
         temp['F'] = 2;
         temp['G'] = 2;
         temp['H'] = 2;
         temp['J'] = 2;
         temp['K'] = 2;
         temp['L'] = 2;
         temp['Q'] = 1;
         temp['W'] = 1;
         temp['E'] = 1;
         temp['R'] = 1;
         temp['T'] = 1;
         temp['Y'] = 1;
         temp['U'] = 1;
         temp['I'] = 1;
         temp['O'] = 1;
         temp['P'] = 1;
         temp['Z'] = 3;
         temp['X'] = 3;
         temp['C'] = 3;
         temp['V'] = 3;
         temp['B'] = 3;
         temp['N'] = 3;
         temp['M'] = 3;
        vector<string> result;
        vector<string>::iterator iter = words.begin();
        for(;iter != words.end();++iter)
        {
            if(isOneRow(*iter,temp))
                 result.push_back(*iter);            
            
        }
        return result;
    }
};