Solving Problem 11720: Sum of NumbersPermalink

Problem DescriptionPermalink

You are given N numbers written consecutively without spaces. Write a program to calculate and print the sum of these numbers.

ConstraintsPermalink

• 1 <= N <= 100
• The input numbers are provided without spaces.

Input FormatPermalink

1. The first line contains an integer N, the number of digits.
2. The second line contains N consecutive digits without spaces.

Output FormatPermalink

• Print the sum of the given digits.

ExamplesPermalink

Example 1Permalink

Input:

1
1

Output:

1

Example 2Permalink

Input:

5
54321

Output:

15

Example 3Permalink

Input:

25
7000000000000000000000000

Output:

7

Example 4Permalink

Input:

11
10987654321

Output:

46

ApproachPermalink

This problem is solved by iterating through each digit of the input string, converting it to an integer, and adding it to a running sum. The approach is straightforward and efficient given the constraint.

Steps to Solve:Permalink

1. Read the input values.
2. Convert the string of numbers into a character array.
3. Loop through each character, convert it to its numeric value, and add it to the sum.
4. Print the total sum.

Java ImplementationPermalink

package datastruc.R1;

import java.util.*;

public class P11720 {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        String sNum = sc.next();

        // Convert string to char array
        char cNum[] = sNum.toCharArray();
        int sum = 0;

        // Sum each digit
        for (int i = 0; i < N; i++) {
            sum += cNum[i] - '0'; // Convert char to int by subtracting '0'
        }

        System.out.println(sum);
        sc.close();
    }
}

Explanation of the CodePermalink

1. Input Handling:
   • Scanner is used to read input.
   • nextInt() reads the number of digits ( N ).
   • next() reads the string of ( N ) digits.
2. Character Array Conversion:
   • The toCharArray() method converts the string into an array of characters, where each character represents a single digit.
3. Summation Loop:
   • Iterate through each character in the array.
   • Convert the character to its integer value by subtracting '0' (ASCII adjustment).
   • Add the integer value to the running total.
4. Output:
   • Print the total sum.

LinksPermalink

• Problem Link: Baekjoon 11720
• Source Code: GitHub Repository

SummaryPermalink

This solution effectively handles the constraints and uses basic string and array manipulation techniques in Java to solve the problem. The time complexity is ( O(N) ), making it efficient given the problem’s limits.