Students Marks Sum - 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.
• Similarly, marks₁, 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.

Complete the function, marks_summation(int* marks, char gender, int number_of_students) which returns the total sum of:

• marks of boys if gender = b
• marks of girls if gender = g

The locked code stub reads the elements of marks along with gender. Then, it calls the function marks_summation(marks, gender, number_of_students) to get the sum of alternate elements as explained above and then prints the sum.

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 marks_i.
• The next line contains gender.

Constraints

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

Output Format

The output should contain the sum of all the aternate elements in marks as explained above.

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 

6

Explanation 1

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

So, sum = marks₁ + marks₃ = 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.

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Students Marks Sum - HackerRank Solution

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

//Complete the following function.

int marks_summation(int * p, int number_of_students, char gender) {
  int s = 0, i = 0;
  if (gender == 'g') {
    i++;
  }
  for (; i < number_of_students; i = i + 2) {
    s += p[i];
  }
  return s;
}
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;
}