Singly Linked List: Deletion Operations

Singly linked list me kisi node ko delete karte waqt do cheezein essential hoti hain: pointers ko accurately reconnect karna taaki list unbroken rahe, aur C me free() function call karke us node ki memory ko heap me release karna taaki Memory Leak na ho.

1. Deletion from Beginning – O(1)

DELETE_FIRST(HEAD)
1. If HEAD == NULL then:
       Print "List Underflow! Empty list."
       Return NULL
2. Set temp = HEAD
3. Set HEAD = HEAD->next
4. Free(temp)
5. Return HEAD

2. Deletion from End – O(n)

Aakhiri node ko delete karne ke liye second-last node tak traverse karna padta hai taaki uske next pointer ko NULL kiya ja sake:

List: [ 10 ] ---> [ 20 ] ---> [ 30 ] ---> NULL
                  ^ prev      ^ temp (Last node)

prev->next = NULL;
free(temp);
New List: [ 10 ] ---> [ 20 ] ---> NULL

3. Deletion by Key Value – O(n)

DELETE_BY_KEY(HEAD, KEY)
1. If HEAD == NULL: Return NULL
2. If HEAD->data == KEY:
       temp = HEAD; HEAD = HEAD->next; free(temp); Return HEAD
3. Set curr = HEAD, prev = NULL
4. While curr != NULL and curr->data != KEY:
       prev = curr; curr = curr->next
5. If curr == NULL: Print "Key not found!"; Return HEAD
6. prev->next = curr->next
7. Free(curr)
8. Return HEAD

Agli post me hum cover karenge Singly Linked List: Reversal and Search Operations.