Delete by Value

Deleting a Node by Value

Deleting a node from the middle of the list requires a previous pointer — you need to update the preceding node's next to skip the deleted node.

struct Node *delete_val(struct Node *head, int val) {
    if (head == NULL) return NULL;
    if (head->val == val) {
        struct Node *next = head->next;
        free(head);
        return next;
    }
    struct Node *prev = head;
    struct Node *cur = head->next;
    while (cur != NULL) {
        if (cur->val == val) {
            prev->next = cur->next;
            free(cur);
            return head;
        }
        prev = cur;
        cur = cur->next;
    }
    return head;
}

The Three Cases

1. List is empty — return NULL
2. Head matches — new head is head->next; free old head
3. Middle/tail matches — set prev->next = cur->next; free cur

Delete 3 from [1] -> [2] -> [3] -> [4] -> NULL
                         prev  cur
                         [2] -> [3] -> [4]
                         [2]  →  ×  →  [4]
Result: [1] -> [2] -> [4] -> NULL

Only the First Occurrence

This removes the first node with the matching value. If duplicates exist, they remain.

Your Task

Implement struct Node *delete_val(struct Node *head, int val) that removes the first occurrence of val and returns the new head.