Sum of numbers formed by consecutive digits present in a given string

Last Updated : 06 Sep, 2021

Given a string S consisting of digits [0 - 9] and lowercase alphabets, the task is to calculate the sum of all numbers represented by continuous sequences of digits present in the string S.

Examples:

Input: S = "11aa32bbb5"
Output: 48
Explanation:
The consecutive sequence of numbers present in the string S are {11, 32, 5}.
Therefore, sum = 11 + 32 + 5 = 48

Input: s = "5an63ff2"
Output: 70

Approach: Follow the steps below to solve the problem:

Initialize a variable, say curr, to store the current sequence of consecutive digits
Iterate over the characters of the string.
If the current character is not a digit, add the current value of curr to the final answer. Reset curr to 0.
Otherwise, append the current digit to curr.
Finally, return the final answer.

Below is the implementation of the above approach:

C++

// C++ Program to implement
// the above approach
#include <bits/stdc++.h>
using namespace std;

// Function to calculate the sum of
// numbers formed by consecutive
// sequences of digits present in the string
int sumOfDigits(string s)
{
    // Stores consecutive digits
    // present in the string
    int curr = 0;

    // Stores the sum
    int ret = 0;

    // Iterate over characters
    // of the input string
    for (auto& ch : s) {

        // If current character is a digit
        if (isdigit(ch)) {

            // Append current digit to curr
            curr = curr * 10 + ch - '0';
        }
        else {

            // Add curr to sum
            ret += curr;

            // Reset curr
            curr = 0;
        }
    }

    ret += curr;
    return ret;
}

// Driver Code
int main()
{
    string S = "11aa32bbb5";
    cout << sumOfDigits(S);
    return 0;
}

Java

// Java program to implement
// the above approach
import java.io.*;
import java.util.*;
class GFG
{

  // Function to calculate the sum of 
  // numbers formed by consecutive 
  // sequences of digits present in the string 
  static int sumOfDigits(String s) 
  { 

    // Stores consecutive digits 
    // present in the string 
    int curr = 0; 

    // Stores the sum 
    int ret = 0; 

    // Iterate over characters 
    // of the input string 
    for(char ch : s.toCharArray())
    { 

      // If current character is a digit 
      if (ch >= 48 && ch <= 57) 
      { 

        // Append current digit to curr 
        curr = curr * 10 + ch - '0'; 
      } 
      else
      { 

        // Add curr to sum 
        ret += curr; 

        // Reset curr 
        curr = 0; 
      } 
    } 
    ret += curr; 
    return ret; 
  } 

  // Driver Code
  public static void main(String[] args)
  {
    String S = "11aa32bbb5";
    System.out.print(sumOfDigits(S));
  }
}

// This code is contributed by splevel62.

Python3

# Python3 program for the above approach

# Function to calculate the sum of
# numbers formed by consecutive
# sequences of digits present in the string
def sumOfDigits(s) :
    
    # Stores consecutive digits
    # present in the string
    curr = 0

    # Stores the sum
    ret = 0

    # Iterate over characters
    # of the input string
    for ch in s :

        # If current character is a digit
        if (ord(ch) >= 48 and ord(ch) <= 57) :

            # Append current digit to curr
            curr = curr * 10 + ord(ch) - ord('0')
        
        else :

            # Add curr to sum
            ret += curr

            # Reset curr
            curr = 0

    ret += curr
    return ret

# Driver Code

S = "11aa32bbb5"
print(sumOfDigits(S))

# This code is contributed by code_hunt.

// C# Program to implement 
// the above approach 
using System;
class GFG
{
    
    // Function to calculate the sum of 
    // numbers formed by consecutive 
    // sequences of digits present in the string 
    static int sumOfDigits(string s) 
    { 
      
        // Stores consecutive digits 
        // present in the string 
        int curr = 0; 
      
        // Stores the sum 
        int ret = 0; 
      
        // Iterate over characters 
        // of the input string 
        foreach(char ch in s)
        { 
      
            // If current character is a digit 
            if (ch >= 48 && ch <= 57) 
            { 
      
                // Append current digit to curr 
                curr = curr * 10 + ch - '0'; 
            } 
            else
            { 
      
                // Add curr to sum 
                ret += curr; 
      
                // Reset curr 
                curr = 0; 
            } 
        } 
        ret += curr; 
        return ret; 
    } 

  // Driver code
  static void Main() {
    string S = "11aa32bbb5";
    Console.WriteLine(sumOfDigits(S));
  }
}

// This code is contributed by divyeshrabadiya07.

JavaScript

<script>

// Javascript Program to implement
// the above approach

// Function to calculate the sum of
// numbers formed by consecutive
// sequences of digits present in the string
function sumOfDigits(s)
{
    // Stores consecutive digits
    // present in the string
    var curr = 0;

    // Stores the sum
    var ret = 0;

    // Iterate over characters
    // of the input string
    s.split('').forEach(ch => {
        
        // If current character is a digit
        if (parseInt(ch)) {

            // Append current digit to curr
            curr = curr * 10 + ch.charCodeAt(0) - '0'.charCodeAt(0);
        }
        else {

            // Add curr to sum
            ret += curr;

            // Reset curr
            curr = 0;
        }
    });

    ret += curr;
    return ret;
}

// Driver Code
var S = "11aa32bbb5";
document.write( sumOfDigits(S));

// This code is contributed by importantly.
</script>

Output:

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

Calculate sum of all numbers present in a string

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Sum of numbers formed by consecutive digits present in a given string

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