键盘手机中按下的按钮计数

给定一个字符串str ，任务是计算如果有一个移动装置(如下图)形成给定的字符串，则总共要计算多少次键被按下。

例子：

Input: str = “abcdef” 
Output: 12 
1 for a, 2 for b, 3 for c, 1 for d, 2 for e and 3 for f 
Total = 1 + 2 + 3 + 1 + 2 + 3 = 12
Input: str = “ssss” 
Output: 16 
 

方法：使用数组来存储按钮有多少次被按下输入特定的字符，然后通过字符遍历给定的字符串的字符，并添加按键的所有相应数量的总和变量。
下面是上述方法的实现：

C++

// C++ implementation of the approach
#include 
using namespace std;
 
// Array to store how many times a button
// has to be pressed for typing
// a particular character
const int arr[] = { 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1,
                    2, 3, 1, 2, 3, 4, 1, 2, 3, 1, 2, 3, 4 };
 
// Function to return the count of
// buttons pressed to type the given string
int countKeyPressed(string str, int len)
{
    int count = 0;
 
    // Count the key presses
    for (int i = 0; i < len; i++)
        count = count + arr[str[i] - 'a'];
 
    // Return the required count
    return count;
}
 
// Driver code
int main()
{
    string str = "abcdef";
    int len = str.length();
    cout << countKeyPressed(str, len);
 
    return 0;
}

Java

// Java implementation of the approach
class GFG {
 
    // Array to store how many times a button
    // has to be pressed for typing
    // a particular character
    static final int arr[] = { 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1,
                               2, 3, 1, 2, 3, 4, 1, 2, 3, 1, 2, 3, 4 };
 
    // Function to return the count of
    // buttons pressed to type the given string
    public static int countKeyPressed(String str, int len)
    {
        int count = 0;
 
        // Count the key presses
        for (int i = 0; i < len; i++)
            count = count + arr[str.charAt(i) - 'a'];
 
        // Return the required count
        return count;
    }
 
    // Driver code
    public static void main(String[] args)
    {
        String str = "abcdef";
        int len = str.length();
        System.out.print(countKeyPressed(str, len));
    }
}

Python3

# Python3 implementation of the approach
 
# Array to store how many times a button
# has to be pressed for typing
# a particular character
arr = [ 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1,
        2, 3, 1, 2, 3, 4, 1, 2, 3, 1, 2, 3, 4 ];
 
# Function to return the count of
# buttons pressed to type the given string
def countKeyPressed(string, length) :
    count = 0;
 
    # Count the key presses
    for i in range(length) :
        count += arr[ord(string[i]) - ord('a')];
 
    # Return the required count
    return count;
 
# Driver code
if __name__ == "__main__" :
    string = "abcdef";
    length = len(string);
     
    print(countKeyPressed(string, length));
 
# This code is contributed by Ryuga

C#

// C# implementation of the approach
using System;
class GFG {
 
    // Array to store how many times a button
    // has to be pressed for typing
    // a particular character
    static readonly int[] arr = { 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1,
                                  2, 3, 1, 2, 3, 4, 1, 2, 3, 1, 2, 3, 4 };
 
    // Function to return the count of
    // buttons pressed to type the given string
    public static int countKeyPressed(String str, int len)
    {
        int count = 0;
 
        // Count the key presses
        for (int i = 0; i < len; i++)
            count = count + arr[str[i] - 'a'];
 
        // Return the required count
        return count;
    }
 
    // Driver code
    public static void Main()
    {
        String str = "abcdef";
        int len = str.Length;
        Console.Write(countKeyPressed(str, len));
    }
}

Javascript

 
 
// Javascript implementation of the approach
 
// Array to store how many times a button
// has to be pressed for typing
// a particular character
var arr = [ 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1,
                    2, 3, 1, 2, 3, 4, 1, 2, 3, 1, 2, 3, 4 ]
 
// Function to return the count of
// buttons pressed to type the given string
function countKeyPressed(str, len)
{
    var count = 0;
 
    // Count the key presses
    for (var i = 0; i < len; i++)
        count = count + arr[str.charCodeAt(i) - 97];
 
    // Return the required count
    return count;
}
 
// Driver code
var str = "abcdef";
var len = str.length;
document.write(countKeyPressed(str, len));
 
// This code is contributed by noob2000.

输出：

12

时间复杂度： O(n)