Generate a string from an array of alphanumeric strings based on given conditions

Given an array of strings arr[] where each string is of the form "name:number" and a character T as input, the task is to generate a new string based on the following conditions:  

• In each string find the maximum digit in "number" which is less than or equal to the length of the string "name".
• If any such digit d is obtained, then append character at index d of the string name to the output string. Otherwise, append character T to the output string.

Examples:  

Input: arr[] = {"Robert:36787", "Tina:68721", "Jo:56389"}, T = 'X' 
Output: tiX 
Explanation: 
For the first string "Robert:36787": Length of "Robert" is 6. Since 6 is present in the string "36787", 6^th character of "Robert", i.e. t is appended to the answer. 
For the second string "Tina:68721": Length of "Tina" is 4. The highest number less than equal to 4, which is present in "68721" is 2. Therefore, 2nd character of "Tina", i.e. i is appended to the answer. 
For the third string "Jo:56389": Length of "Jo" is 2. Since no number less than equal to 2 is present in "56389", T( = 'X') is appended to the answer. 
Therefore, the final string after the above operations is "tiX".
Input: arr[] = {"Geeks:89167", "gfg:68795"}, T = 'X' 
Output: GX 
Explanation: 
For the first string "Geeks:89167", length of "Geeks" = 5 and the "89167" number has digit 1 which is less than 5. 
So, the resultant string will have the character at the 1st position of the name, which is 'G'. 
For the second string "gfg:68795", the length of "gfg" = 3, and the "68795" doesn't have a digit less than or equals to 3. 
So, the resultant string will have the character T. 
Therefore, the final string after the above operations is "GX". 
 

Approach: To solve the problem follow the steps given below:  

1. Traverse through the array of strings and split each string around ":". The first part contains the name and the second part contains the number.
2. Store the length of the name in a variable and find the maximum digit less than or equal to the length of the number.
3. If any such digit found is found, extract the character at that index of name and append to the resultant string. Otherwise, append T to the resultant string.
4. Print the resultant string after repeating the above operations for all the strings in the array.

Below is the implementation of the above approach:

// C++ program for the 
// above approach
#include<bits/stdc++.h>
using namespace std;
    
// Function to generate required string
string generatePassword(vector<string>arr, 
                        char T)
{
  // To store the result
  string result;
  for (auto s:arr) 
  {
    // Split name and number
    int index;
    
    for(int i = 0; i < s.size(); i++)
    {
      if(s[i] == ':')
      {
        index = i;
        break;
      }
    }
    
    string name = s.substr(0, index);
    string number = s.substr(index + 1, 
                             s.size() - 
                             index - 1);
    int n = name.length(); 
    
    // Stores the maximum number
    // less than or equal to the
    // length of name
    int max = 0;

    for (int i = 0; i < number.length(); i++) 
    {
      // Check for number by parsing
      // it to integer if it is greater
      // than max number so far
      int temp = number[i] - '0';

      if (temp > max && temp <= n)
        max = temp;
    }

    // Check if no such number is
    // found then we append X
    // to the result.
    if (max == 0)
      result.push_back(T);

    // Otherwise
    else

      // Append max index
      // of the name
      result.push_back(name[max - 1]);
  }

  // Return the final string
  return result;
}

// Driver Code
int main()
{
  vector<string>arr = {"Geeks:89167",
                       "gfg:68795"};
  char T = 'X';

  // Function Call
  cout << (generatePassword(arr, T));
}

// This code is contributed by Stream_Cipher

// Java program for the above approach

import java.io.*;

class GFG {

    // Function to generate required string
    public static String
    generatePassword(String s[], char T)
    {
        // To store the result
        StringBuilder result
            = new StringBuilder();

        for (String currentString : s) {

            // Split name and number
            String person[]
                = currentString.split(":");
            String name = person[0];
            String number = person[1];

            int n = name.length();

            // Stores the maximum number
            // less than or equal to the
            // length of name
            int max = 0;

            for (int i = 0;
                 i < number.length(); i++) {

                // Check for number by parsing
                // it to integer if it is greater
                // than max number so far
                int temp = Integer.parseInt(
                    String.valueOf(number.charAt(i)));

                if (temp > max && temp <= n)
                    max = temp;
            }

            // Check if no such number is
            // found then we append X
            // to the result.
            if (max == 0)
                result.append(T);

            // Otherwise
            else

                // Append max index
                // of the name
                result.append(
                    String.valueOf(
                        name.charAt(max - 1)));
        }

        // Return the final string
        return result.toString();
    }

    // Driver Code
    public static void
        main(String[] args)
    {
        String arr[] = { "Geeks:89167",
                         "gfg:68795" };
        char T = 'X';

        // Function Call
        System.out.println(
            generatePassword(arr, T));
    }
}

# Python3 program for 
# the above approach 

# Function to generate
# required string 
def generatePassword(s, T):

    # To store the result
    result = []
    
    for currentString in s:

        # Split name and number
        person = currentString.split(":")
        name = person[0]
        number = person[1]
        n = len(name)

        # Stores the maximum number 
        # less than or equal to the 
        # length of name
        max = 0

        for i in range(len(number)):

            # Check for number by parsing 
            # it to integer if it is greater 
            # than max number so far 
            temp = int(number[i])

            if(temp > max and temp <= n):
                max = temp

        # Check if no such number is 
        # found then we append X 
        # to the result.
        if max == 0:
            result.append(T)

        # Otherwise
        else:

            # Append max index 
            # of the name 
            result.append(name[max - 1])

    # Return the 
    # final string
    return result

# Driver Code 
arr = ["Geeks:89167","gfg:68795"]
T = 'X'

# Function call
print(*generatePassword(arr, T), 
       sep = "")

# This code is contributed by avanitrachhadiya2155

// C# program for the above approach
using System;
using System.Text;
class GFG{

// Function to generate required string
public static String generatePassword(String []s, 
                                      char T)
{
    // To store the result
    StringBuilder result = new StringBuilder();
    foreach (String currentString in s) 
    {
        // Split name and number
        String []person = currentString.Split(':');
        String name = person[0];
        String number = person[1];

        int n = name.Length;

        // Stores the maximum number
        // less than or equal to the
        // length of name
        int max = 0;

        for (int i = 0; i < number.Length; i++) 
        {
            // Check for number by parsing
            // it to integer if it is greater
            // than max number so far
            int temp = Int32.Parse(String.Join("", 
                                   number[i]));
            if (temp > max && temp <= n)
                max = temp;
        }

        // Check if no such number is
        // found then we append X
        // to the result.
        if (max == 0)
            result.Append(T);

        // Otherwise
        else

            // Append max index
            // of the name
            result.Append(String.Join("", 
                          name[max - 1]));
    }

    // Return the readonly string
    return result.ToString();
}

// Driver Code
public static void Main(String[] args)
{
    String []arr = {"Geeks:89167",
                    "gfg:68795"};
    char T = 'X';

    // Function Call
    Console.WriteLine(generatePassword(arr, T));
}
}

// This code is contributed by shikhasingrajput 

<script>
      // JavaScript program for the above approach
      // Function to generate required string
      function generatePassword(s, T) {
        // To store the result
        var result = [];

        for (const currentString of s) {
          // Split name and number
          var person = currentString.split(":");
          var name = person[0];
          var number = person[1];

          var n = name.length;

          // Stores the maximum number
          // less than or equal to the
          // length of name
          var max = 0;

          for (var i = 0; i < number.length; i++) {
            // Check for number by parsing
            // it to integer if it is greater
            // than max number so far
            var temp = parseInt(number[i]);
            if (temp > max && temp <= n) max = temp;
          }

          // Check if no such number is
          // found then we append X
          // to the result.
          if (max === 0) result.push(T);
          // Otherwise
          // Append max index
          // of the name
          else result.push(name[max - 1]);
        }

        // Return the readonly string
        return result.join("");
      }

      // Driver Code
      var arr = ["Geeks:89167", "gfg:68795"];
      var T = "X";

      // Function Call
      document.write(generatePassword(arr, T) + "<br>");
      
      // This code is contributed by rdtank.
    </script>

GX

Time Complexity: O(N) 
Auxiliary Space: O(1)