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  1. #include <iostream>
  2. #include <string>
  3.  
  4. using namespace std;
  5.  
  6. struct node {
  7. 	int value;
  8. 	node * next;
  9. 	node(int v, node * n = NULL) {
  10. 		value = v;
  11. 		next = n;
  12. 	}
  13. };
  14.  
  15. struct chain {
  16. 	node * head;
  17. 	int count;
  18. 	chain(node * h = NULL) {
  19. 		head = h;
  20. 		count = 0;
  21. 	}
  22. 	~chain() {
  23. 		clear();
  24. 	}
  25. 	int push(int v) {
  26. 		head = new node(v, head);
  27. 		++count;
  28. 		return v;
  29. 	}
  30. 	int pop() {
  31. 		int v = head->value;
  32. 		node * n = head;
  33. 		head = head->next;
  34. 		delete n;
  35. 		--count;
  36. 		return v;
  37. 	}
  38. 	int back() {
  39. 		return head->value;
  40. 	}
  41. 	void clear() {
  42. 		while(head != NULL) pop();
  43. 	}
  44. 	int size() {
  45. 		return count;
  46. 	}
  47. 	bool empty() {return !count;}
  48. } stack;
  49.  
  50. int main() {
  51. 	string s;
  52. 	while (cin >> s) {
  53. 		if (s == "exit") {cout << "bye\n"; return 0;}
  54. 		if (s == "push") {int x; cin >> x; stack.push(x); cout << "ok\n";}
  55. 		if (s == "pop") 
  56. 			if (stack.empty()) cout << "error" << endl;
  57. 			else cout << stack.pop() << endl;
  58. 		if (s == "back") 
  59. 			if (stack.empty()) cout << "error" << endl;
  60. 			else cout << stack.back() << endl;
  61. 		if (s == "clear") {stack.clear(); cout << "ok\n";}
  62. 		if (s == "size") {cout << stack.size() << endl;}
  63. 	}
  64. }
Success #stdin #stdout 0s 5496KB
comments (?)
stdin
copy 
push 2
push 3
push 5
back
size
pop
size
push 7
pop
clear
size
exit
stdout
copy 
ok
ok
ok
5
3
5
2
ok
7
ok
0
bye
https://ideone.com/JrLsIy
https://w...content-available-to-author-only...p.com/ru/problems/6124
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
public

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