题目

问题链接：https://leetcode.com/problems/keyboard-row/#/description
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:
You may use one character in the keyboard more than once.
You may assume the input string will only contain letters of alphabet.

思路

1. 用Map存储字母到所在行的映射。
2. 变量words，对每一个单词，先做小写字母转换存入word，再对word的每个字母进行遍历。用flag标记是否是第一个字母，用row存储第一个字母所在的行，对后续的字母，判断其所在行是否等于row，若不是，直接跳出内层循环继续判断下一个单词。考虑到数组需要预先设置长度，而数组长度未知，所以判断整个单词完毕后将其县存入List，最后再把List的元素存入结果数组。

代码

keyboardRow.go

package _500_Keyboard_Row

import (
    "fmt"
    "strings"
)

var alphabetMap map[string]int

func init() {
    alphabetMap = make(map[string]int)
    row1 := []string{"q", "w", "e", "r", "t", "y", "u", "i", "o", "p"}
    row2 := []string{"a", "s", "d", "f", "g", "h", "j", "k", "l"}
    for _, v := range row1 {
        alphabetMap[v] = 1
    }
    for _, v := range row2 {
        alphabetMap[v] = 2
    }
}
func findWord(word string) (ret bool) {
    word = strings.ToLower(word)
    var allRow int
    allRow = alphabetMap[word[:1]]
    length := len(word)
    for i := 1; i < length; i++ {
        row := alphabetMap[word[i:i+1]]

        if allRow != row {
            return false
        }
    }

    return true
}

func FindWords(words []string) []string {
    var ret []string

    for _, v := range words {
        ok := findWord(v)
        if ok {
            ret = append(ret, v)
        }
    }
    fmt.Printf("ret:%+v\n", ret)
    return ret
}

测试

keyboardRow_test.go

package _500_Keyboard_Row

import "testing"

func TestFindWords(t *testing.T) {

    words := []string{
        "Hello", "Alaska", "Dad", "Peace"}
    ret := FindWords(words)

    wanted := map[string]int{
        "Alaska": 1,
        "Dad": 2,
    }

    for _, v := range ret {
        _, ok := wanted[v]

        if !ok {
            t.Errorf("fail, not want but have %+v\n", v)
            return
        }
    }

    t.Logf("pass")
}

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