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  1. // our task is to create a vector now
  2. #include<bits/stdc++.h>
  3. using namespace std;
  4.  
  5. class Node {
  6.     public:
  7.         int value;
  8.         Node* next;
  9.         Node* prev;
  10.     Node() {
  11.         value = 0;
  12.         next = NULL;
  13.         prev = NULL;
  14.     }
  15.     Node(int value) {
  16.         this->value = value;
  17.         next = NULL;
  18.         prev = NULL;
  19.     }
  20.     void setNext(Node* next) {
  21.         this->next = next;
  22.     }
  23.     void setPrev(Node* prev) {
  24.         this->prev = prev;
  25.     }
  26.     void setValue(int value) {
  27.         this->value = value;
  28.     }
  29. };
  30.  
  31. class Vector {
  32.     public:
  33.         Node* head;
  34.         Node* tail;
  35.     Vector() {
  36.         head = new Node();
  37.         tail = head;
  38.     }
  39.  
  40.     // tail = 'banani'
  41.     // newNode = 'shewrapara'
  42.     // tail-next = newnode = 'shewrapara'
  43.     // newPrev->prev = tail = 'banani'
  44.     // tail = 'shewrapara'
  45.     void push_back(int value) {
  46.         Node* newNode = new Node(value);
  47.         tail->next = newNode;
  48.         newNode->prev = tail;
  49.         tail = newNode;
  50.     }
  51.     void pop_back() {
  52.         if(tail == head) {
  53.             cerr << "vector is empty, so your can't pop" << endl;
  54.             return; // vector is empty so nothing to pop
  55.         }
  56.         tail = tail->prev;
  57.         tail->next = NULL;
  58.     }
  59.     int back() {
  60.         if(tail == head) {
  61.             cerr << "vector is empty, so your can't pop" << endl;
  62.             return -1;
  63.         }
  64.         return tail->value;
  65.     }
  66.     int front() {
  67.         if(head->next == NULL) {
  68.             cerr << "vector is empty, so your can't pop" << endl;
  69.             return -1;
  70.         }
  71.         return head->next->value;
  72.     }
  73.  
  74.     void push_front(int value)
  75.     {
  76.         Node* newNode = new Node(value);
  77.         newNode->next = head->next;
  78.         newNode->prev = head;
  79.         head->next = newNode;
  80.     }
  81.  
  82.     void pop_front()
  83.     {
  84.         if(head->next == NULL){
  85.             cerr << "Vector is empty so you cannot pop front" << endl;
  86.             return;
  87.         } 
  88.         Node* del_node = head->next;
  89.         head->next = del_node->next;
  90.         if(del_node->next != NULL)
  91.         {
  92.             del_node->next->prev = head;
  93.         }
  94.     }
  95. };
  96.  
  97. int main() {
  98.     Vector v;
  99.     v.push_back(5);
  100.     cout << v.front() << endl;
  101.     v.pop_front();
  102.     cout << v.front() << endl;
  103.     v.pop_front();
  104.     v.push_front(10101);
  105.     cout << v.front() << endl;
  106. }
Success #stdin #stdout #stderr 0.01s 5292KB
comments (?)
stdin
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Standard input is empty
stdout
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5
-1
10101
stderr
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vector is empty, so your can't pop
Vector is empty so you cannot pop front
https://ideone.com/z3uo2Q
language:
C++14 (gcc 8.3)
created:
8 days ago
visibility:
public

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