Question

Write a function that operates on a binary tree of integers. Your function should sum up the all of the even numbers in the tree EXCEPT for the numbers in leaf nodes, which should instead be ignored. Make use of the function prototype shown below. int sum_nonleaf_even(struct treenode* p); B IV AA- IX EX 1 1 1 XX, E = 2 V 1 12pt - Paragraph - O words

Answer 1

// This is the struct definition I used
struct treenode {
    int value;
    struct treenode *left;
    struct treenode *right;
};

int sum_nonleaf_even(struct treenode *p) {
    if (p == NULL) return 0;    // if tree is empty, return 0
    // calculates the sum recursively from left and right subtrees
    int total_even = sum_nonleaf_even(p->left) + sum_nonleaf_even(p->right);

    // if the node has even value and not a leaf, then add the value to total
    if (p->value % 2 == 0 && (p->left != NULL || p->right != NULL))
        total_even += p->value;
    return total_even;  // return the total value calculated
}