Given a string S of size N, consisting of digits [0 – 9] and character ‘.’, the task is to print the string that can be obtained by pressing the mobile keypad in the given sequence.
Note: ‘.’ represents a break while typing.
Below is the image to represent the characters associated with each number in the keypad.
Examples:
Input: S = “234”
Output: ADG
Explanation:
Pressing the keys 2, 3, and 4 once gives the resultant string as “ADG”.Input: S = “22.22”
Output: BB
Explanation:
Pressing the key 2 twice gives B, and then again pressing the key twice gives B. Therefore, the resultant string is “BB”.
Approach: The given problem can be solved by storing the mobile keypad mappings in an array and then traverse the string S and convert it into its equivalent string. Follow the steps below to solve the problem:
- Initialize an empty string, say ans to store the required result.
- Store the string associated to each key in the mobile keypad in an array nums[] such that nums[i] represent the set of characters on pressing the digit i.
- Traverse the given string S using the variable i and perform the following steps:
- If S[i] is equal to ‘.’, then increment i by 1, and continue to the next iteration.
- Otherwise, initialize a variable cnt as 0 to store the count of the same characters.
- Iterate until S[i] is equal to S[i + 1] and in each iteration check the following conditions:
- If cnt is equal to 2 and S[i] is 2, 3, 4, 5, 6, or 8, then break out of the loop because keys: 2, 3, 4, 5, 6, and 8 contain the same number of characters, i.e., 3.
- If cnt is equal to 3 and S[i] is 7 or 9, then break out of the loop because keys: 7 and 9 contain the same number of characters, i.e., 4.
- Increment the value of cnt and i by 1.
- If S[i] is either 7 or 9, then add the character nums[str[i]][cnt%4] to the string ans.
- Otherwise, add the character nums[str[i]][cnt%3] to the string ans.
- Increment the value of i by 1.
- After completing the above steps, print the value string ans as the result.
Below is the implementation of the above approach:
C++
// C++ program for the above approach#include <bits/stdc++.h>using namespace std;// Function to convert mobile numeric// keypad sequence into its equivalent// stringvoid printSentence(string str){ // Store the mobile keypad mappings char nums[][5] = { "", "", "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ" }; // Traverse the string str int i = 0; while (str[i] != '\0') { // If the current character is // '.', then continue to the // next iteration if (str[i] == '.') { i++; continue; } // Stores the number of // continuous clicks int count = 0; // Iterate a loop to find the // count of same characters while (str[i + 1] && str[i] == str[i + 1]) { // 2, 3, 4, 5, 6 and 8 keys will // have maximum of 3 letters if (count == 2 && ((str[i] >= '2' && str[i] <= '6') || (str[i] == '8'))) break; // 7 and 9 keys will have // maximum of 4 keys else if (count == 3 && (str[i] == '7' || str[i] == '9')) break; count++; i++; // Handle the end condition if (str[i] == '\0') break; } // Check if the current pressed // key is 7 or 9 if (str[i] == '7' || str[i] == '9') { cout << nums[str[i] - 48][count % 4]; } // Else, the key pressed is // either 2, 3, 4, 5, 6 or 8 else { cout << nums[str[i] - 48][count % 3]; } i++; }}// Driver Codeint main(){ string str = "234"; printSentence(str); return 0;} |
Java
// java program for the above approachimport java.io.*;import java.lang.*;import java.util.*;public class GFG { // Function to convert mobile numeric // keypad sequence into its equivalent // string static void printSentence(String S) { // Store the mobile keypad mappings String nums[] = { "", "", "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ" }; char str[] = S.toCharArray(); // Traverse the string str int i = 0; while (i < str.length) { // If the current character is // '.', then continue to the // next iteration if (str[i] == '.') { i++; continue; } // Stores the number of // continuous clicks int count = 0; // Iterate a loop to find the // count of same characters while (i + 1 < str.length && str[i] == str[i + 1]) { // 2, 3, 4, 5, 6 and 8 keys will // have maximum of 3 letters if (count == 2 && ((str[i] >= '2' && str[i] <= '6') || (str[i] == '8'))) break; // 7 and 9 keys will have // maximum of 4 keys else if (count == 3 && (str[i] == '7' || str[i] == '9')) break; count++; i++; // Handle the end condition if (i == str.length) break; } // Check if the current pressed // key is 7 or 9 if (str[i] == '7' || str[i] == '9') { System.out.print( nums[str[i] - 48].charAt(count % 4)); } // Else, the key pressed is // either 2, 3, 4, 5, 6 or 8 else { System.out.print( nums[str[i] - 48].charAt(count % 3)); } i++; } } // Driver Code public static void main(String[] args) { String str = "234"; printSentence(str); }}// This code is contributed by Kingash. |
Python3
# Python3 program for the above approach# Function to convert mobile numeric# keypad sequence into its equivalent# stringdef printSentence(str1): # Store the mobile keypad mappings nums = [ "", "", "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ" ] # Traverse the string str1 i = 0 while (i < len(str1)): # If the current character is # '.', then continue to the # next iteration if (str1[i] == '.'): i += 1 continue # Stores the number of # continuous clicks count = 0 # Iterate a loop to find the # count of same characters while (i + 1 < len(str1) and str1[i + 1] and str1[i] == str1[i + 1]): # 2, 3, 4, 5, 6 and 8 keys will # have maximum of 3 letters if (count == 2 and ((str1[i] >= '2' and str1[i] <= '6') or (str1[i] == '8'))): break # 7 and 9 keys will have # maximum of 4 keys elif (count == 3 and (str1[i] == '7' or str1[i] == '9')): break count += 1 i += 1 # Handle the end condition if (i < len(str)): break # Check if the current pressed # key is 7 or 9 if (str1[i] == '7' or str1[i] == '9'): print(nums[ord(str1[i]) - 48][count % 4], end = "") # Else, the key pressed is # either 2, 3, 4, 5, 6 or 8 else: print(nums[ord(str1[i]) - 48][count % 3], end = "") i += 1# Driver Codeif __name__ == '__main__': str1 = "234" printSentence(str1)# This code is contributed by bgangwar59 |
C#
// C# program for the above approachusing System;public class GFG{ // Function to convert mobile numeric // keypad sequence into its equivalent // string static void printSentence(string S) { // Store the mobile keypad mappings string[] nums = { "", "", "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ" }; char[] str = S.ToCharArray(); // Traverse the string str int i = 0; while (i < str.Length) { // If the current character is // '.', then continue to the // next iteration if (str[i] == '.') { i++; continue; } // Stores the number of // continuous clicks int count = 0; // Iterate a loop to find the // count of same characters while (i + 1 < str.Length && str[i] == str[i + 1]) { // 2, 3, 4, 5, 6 and 8 keys will // have maximum of 3 letters if (count == 2 && ((str[i] >= '2' && str[i] <= '6') || (str[i] == '8'))) break; // 7 and 9 keys will have // maximum of 4 keys else if (count == 3 && (str[i] == '7' || str[i] == '9')) break; count++; i++; // Handle the end condition if (i == str.Length) break; } // Check if the current pressed // key is 7 or 9 if (str[i] == '7' || str[i] == '9') { Console.Write(nums[str[i] - 48][count % 4]); } // Else, the key pressed is // either 2, 3, 4, 5, 6 or 8 else { Console.Write(nums[str[i] - 48][count % 3]); } i++; } } // Driver Code public static void Main(string[] args) { string str = "234"; printSentence(str); }}// This code is contributed by ukasp. |
Javascript
<script>// Javascript program for the above approach// Function to convert mobile numeric// keypad sequence into its equivalent// stringfunction printSentence(S) { // Store the mobile keypad mappings let nums = [ "", "", "ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ"]; let str = S.split(""); // Traverse the string str let i = 0; while (i < str.length) { // If the current character is // '.', then continue to the // next iteration if (str[i] == '.') { i++; continue; } // Stores the number of // continuous clicks let count = 0; // Iterate a loop to find the // count of same characters while (i + 1 < str.length && str[i] == str[i + 1]) { // 2, 3, 4, 5, 6 and 8 keys will // have maximum of 3 letters if (count == 2 && ((str[i] >= '2' && str[i] <= '6') || (str[i] == '8'))) break; // 7 and 9 keys will have // maximum of 4 keys else if (count == 3 && (str[i] == '7' || str[i] == '9')) break; count++; i++; // Handle the end condition if (i == str.length) break; } // Check if the current pressed // key is 7 or 9 if (str[i] == '7' || str[i] == '9') { document.write( nums[str[i].charCodeAt(0) - 48][count % 4]); } // Else, the key pressed is // either 2, 3, 4, 5, 6 or 8 else { document.write( nums[str[i].charCodeAt(0) - 48][count % 3]); } i++; }}// Driver Codelet str = "234";printSentence(str);// This code is contributed by _saurabh_jaiswal.</script> |
Output:
ADG
Time Complexity: O(N)
Auxiliary Space: O(1)
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