Student Marks Sum in C Hackerrank Solution

 You are given an array of integers, marks , denoting the marks scored by students in a class.

• The alternating elements marks0, marks2, marks4 and so on denote the marks of boys.
• Similarlymarks1, marks3, marks5 and so on denote the marks of girls.

The array name, marks, works as a pointer which stores the base address of that array. In other words,  marks  contains the address where marks0 is stored in the memory.

For example, let marks = [3,2,5] and marks stores 0x7fff9575c05f. Then, 0x7fff9575c05f is the memory address of  marks0 .

Function Description

Complete the function, marks_summation in the editor below.

marks_summation has the following parameters:

• int marks[number_of_students]: the marks for each student
• int number_of_students: the size of marks[]
• char gender: either ‘g’ or ‘b’

Returns

• int: the sum of marks for boys if gender=b , or of marks of girls if gender=g.

Input Format

• The first line contains number_of_students, denoting the number of students in the class, hence the number of elements in marks.
• Each of the number_of_students subsequent lines contains marksi.
• The next line contains gender.

Constraints

• 1 < number_of_students < 103
• 1 < marksi < 103 (where 0 < i < number_of_students)
• gender = g or b 

Sample Input 0

3
3
2
5
b

Sample Output 0

8

Explanation 0

marks = [3, 2, 5] and gender = b.

So, marks0 + marks2 = 3+5 = 8.

Sample Input 1

5
1
2
3
4
5
g

Sample Output 1

6

Explanation 1

marks  = [1, 2, 3, 4, 5] and gender = g

So, sum = marks1 + marks2  = 2+5 = 8

Sample Input 2

1
5
g

Sample Output 2

0

Explanation 2

 marks = [5] and gender = g

Here, marks1 does not exist. So, sum = 0.

Code

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

//Complete the following function.

int marks_summation(int* marks, int number_of_students, char gender) 
{
  //Write your code here.
  int sum = 0;
    for (int i = (gender == 'b' ? 0 : 1); i < number_of_students; i = i + 2) 
        sum += *(marks + i);
    
    return sum;
}
int main() {
    int number_of_students;
    char gender;
    int sum;
  
    scanf("%d", &number_of_students);
    int *marks = (int *) malloc(number_of_students * sizeof (int));
 
    for (int student = 0; student < number_of_students; student++) {
        scanf("%d", (marks + student));
    }
    
    scanf(" %c", &gender);
    sum = marks_summation(marks, number_of_students, gender);
    printf("%d", sum);
    free(marks);
 
    return 0;
}