Sum of Numbers in String

Problem

Given a string str containing alphanumeric characters. The task is to calculate the sum of all the numbers present in the string.

Examples:

Example 1:

Input:
str = 1abc23
Output: 24
Explanation: 1 and 23 are numbers in the string which is added to get the sum as 24.

Example 2:

Input:
str = geeks4geeks
Output: 4
Explanation: 4 is the only number, so the sum is 4.

Your task:

The task is to complete the function findSum() which finds and returns the sum of numbers in the string.

• Expected Time Complexity: $O(N)$
• Expected Auxiliary Space: $O(N)$

Constraints:

• $1<=$ length of the string $<=10^5$
• Sum of Numbers $<=10^5$

Solution

Python

def findSum(self,s):
    temp = "0"
    Sum = 0
    for ch in s:
        if (ch.isdigit()):
            temp += ch
        else:
            Sum += int(temp)
            temp = "0"
    return Sum + int(temp)

Java

public static long findSum(String str) {
    String temp = "0";
    long Sum = 0;
    for (char ch : str.toCharArray()) {
        if (Character.isDigit(ch)) {
            temp += ch;
        } 
        else {
            Sum += Long.parseLong(temp);
            temp = "0";
        }
    }
    
    Sum += Long.parseLong(temp);
    return Sum;
}

C++

int findSum(string str) {
    string temp = "0";
    int Sum = 0;
    for (char ch : str) {
        if (isdigit(ch)) {
            temp += ch;
        } 
        else {
            Sum += stoi(temp);
            temp = "0";
        }
    }
    Sum += stoi(temp);
    return Sum;
}

C

int findSum(const char *str) {
    char temp[20];   
    int Sum = 0;
    int temp_index = 0;
    for (const char *ptr = str; *ptr != '\0'; ptr++) {
        if (isdigit(*ptr)) {
            temp[temp_index++] = *ptr;
        } 
        else {
            temp[temp_index] = '\0';  
            Sum += atoi(temp);        
            temp_index = 0;           
        }
    }
    temp[temp_index] = '\0';  
    Sum += atoi(temp);        
    return Sum;
}

• Time Complexity: $O(N)$
• Auxiliary Space: $O(N)$