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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. struct node {
  5. 	int value;
  6. 	node *next;
  7. };
  8.  
  9. int main() {
  10. 	node *head = new node;
  11. 	head->next = NULL;
  12. 	node *last = NULL;
  13.  
  14. 	int choice, n;
  15. 	cout << "Enter 1 to enqueue, 2 to dequeue, 0 to exit: ";
  16. 	while(1) {
  17. 		cin >> choice;
  18. 		if(choice == 1) {
  19. 			cout << "Enter the num: ";
  20. 			cin >> n;
  21. 			node *p = new node;
  22. 			p->value = n;
  23. 			p->next = NULL;
  24. 			if(last != NULL) {
  25. 				last->next = p;
  26. 				last = p;
  27. 			}
  28. 			else {
  29. 				head->next = p;
  30. 				last = p;
  31. 			}
  32. 		}
  33. 		else if(choice == 2) {
  34. 			if(head->next == NULL) {
  35. 				cout << "List is empty!" << endl;
  36. 			}
  37. 			else {
  38. 				cout << "Dequeued num: " << head->next->value << endl;
  39. 				head->next = head->next->next;
  40. 				if(head->next == NULL) {
  41. 					last = NULL;
  42. 				}
  43. 			}
  44. 		}
  45. 		else {
  46. 			break;
  47. 		}
  48. 	}
  49. 	return 0;
  50. }
Success #stdin #stdout 0s 3472KB
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stdin
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Standard input is empty
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Enter 1 to enqueue, 2 to dequeue, 0 to exit:
https://ideone.com/ZPsEO2
Implementing a queue using a singly linked list, supporting enqueue and dequeue operations in O(1) time.
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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