List Mixed

Difficulty: ⚫⚫◯◯

Tags: linked-list, traversal, even-odd

Hurdle: Passing this question is sufficient to pass the linked lists hurdle.

Description

Write a function mixed that is given one argument: head, a pointer to the first node of a linked list.

The function should return:

• 1 if the linked list contains both even and odd numbers
• 0 otherwise

Examples

Example 1: Contains Both

List: 16 -> 12 -> 8 -> 3 -> 6 -> 12 -> X

Output: 1

Explanation: The list contains 3 (odd) and 16, 12, 8, 6, 12 (even). Since it has both, return 1.

Example 2: Only Even

List: 16 -> 12 -> 8 -> 6 -> 12 -> X

Output: 0

Explanation: The list contains only even numbers, so return 0.

Example 3: Only Odd

List: 3 -> 1 -> X

Output: 0

Explanation: The list contains only odd numbers (3, 1), so return 0.

Example 4: Mixed

List: 3 -> 1 -> 4 -> X

Output: 1

Explanation: Contains 3, 1 (odd) and 4 (even), so return 1.

Example 5: Mixed

List: 1 -> 2 -> 3 -> 4 -> X

Output: 1

Explanation: Contains both odd (1, 3) and even (2, 4) numbers.

Example 6: Single Element

List: 42 -> X

Output: 0

Explanation: Only one even number, no odd numbers present.

Example 7: Empty List

List: (empty)

Output: 0

Explanation: Empty list has neither even nor odd numbers.

Function Signature

int mixed(struct node *head);

Data Structure

struct node {
    struct node *next;
    int          data;
};

Constraints

• Return only 1 or 0.
• Do not change the linked list provided.
• Do not change the next or data fields of list nodes.
• Do not use arrays.
• Do not call malloc.
• Do not call scanf, getchar, or fgets.
• Do not call printf.

Hints

• Use two flags: one to track if you've seen an even number, one for odd.
• A number is even if data % 2 == 0, odd otherwise.
• Return 1 only if both flags are set.

Testing

./list-mixed 3 1 4
1

./list-mixed 3 1
0

./list-mixed 2 4 6 42
0

./list-mixed 1 2 3 4
1

./list-mixed 42
0

./list-mixed
0

./list-mixed 16 12 8 3 6 12
1

./list-mixed 16 12 8 6 12
0