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  1. #include<iostream>
  2.  
  3. using namespace std;
  4.  
  5. struct node
  6. {
  7.     int value;
  8.     struct node *next;
  9. };
  10. struct node *head = NULL;
  11. struct node *tail = NULL;
  12.  
  13. void insertHead(int val)
  14. {
  15.     //create a new node
  16.     struct node *newItem;
  17.     newItem=(struct node *)malloc(sizeof(struct node));
  18.     newItem->value = val;
  19.     newItem->next = NULL;
  20.  
  21.     if (head == NULL) tail = newItem;
  22.     //insert the new node at the head
  23.     newItem->next = head;
  24.     head = newItem;
  25. }
  26. void insertTail(int val)
  27. {
  28.     //create a new node to be inserted
  29.     struct node *newItem;
  30.     newItem=(struct node *)malloc(sizeof(struct node));
  31.     newItem->value = val;
  32.     newItem->next = NULL;
  33.     if (head == NULL)
  34.     {
  35.         head = newItem;
  36.         tail = newItem;
  37.         return;
  38.     }
  39.  
  40.     newItem->next = NULL;
  41.     tail->next = newItem;
  42.     tail = newItem;
  43. }
  44. void printList()
  45. {
  46.     if (head == NULL) return;
  47.     struct node *cur =  head;
  48.     while (cur != NULL)
  49.     {
  50.         printf("%d \t", cur->value);
  51.         cur = cur->next;
  52.     }
  53. }
  54. int deleteHead()
  55. {
  56.     struct node *cur;
  57.     if (head == NULL) return -1;
  58.     cur = head;
  59.     head = head->next;
  60.  
  61.     if (head == NULL) tail = NULL;
  62.  
  63.     int val = cur->value;
  64.     free(cur);
  65.     return val;
  66. }
  67.  
  68. class QUEUE{
  69.     node* front;
  70.     node* rear;
  71.  
  72. public:
  73.     QUEUE(){
  74.         front = NULL;
  75.         rear = NULL;
  76.     }
  77.  
  78.     void push_back(int val){
  79.         //create a new node to be inserted
  80.         struct node *newItem;
  81.         newItem=(struct node *)malloc(sizeof(struct node));
  82.         newItem->value = val;
  83.         newItem->next = NULL;
  84.         if (front == NULL)
  85.         {
  86.             front = newItem;
  87.             rear = newItem;
  88.             return;
  89.         }
  90.  
  91.         newItem->next = NULL;
  92.         rear->next = newItem;
  93.         rear = newItem;
  94.     }
  95.  
  96.     int pop(){
  97.         struct node *cur;
  98.         if (front == NULL) return -1;
  99.         cur = front;
  100.         front = front->next;
  101.  
  102.         if (front == NULL) rear = NULL;
  103.  
  104.         int val = cur->value;
  105.         free(cur);
  106.         return val;
  107.     }
  108. };
  109.  
  110.  
  111. int main(){
  112.     QUEUE q;
  113.     q.push_back(10);
  114.     q.push_back(20);
  115.     q.push_back(30);
  116.  
  117.     cout<<q.pop()<<endl;
  118.     cout<<q.pop()<<endl;
  119.     cout<<q.pop()<<endl;
  120.     cout<<q.pop()<<endl;
  121. }
  122.  
Success #stdin #stdout #stderr 0.01s 5320KB
comments (?)
stdin
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Standard input is empty
stdout
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Standard output is empty
stderr
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Error: near line 3: near "using": syntax error
Error: near line 5: near "struct": syntax error
Error: near line 8: near "struct": syntax error
Error: near line 9: unrecognized token: "}"
Error: near line 10: near "struct": syntax error
Error: near line 11: near "struct": syntax error
Error: near line 13: near "void": syntax error
Error: near line 17: near "newItem": syntax error
Error: near line 18: near "newItem": syntax error
Error: near line 19: near "newItem": syntax error
Error: near line 21: near "if": syntax error
Error: near line 22: near "/": syntax error
Error: near line 24: near "head": syntax error
Error: near line 25: unrecognized token: "}"
Error: near line 30: near "newItem": syntax error
Error: near line 31: near "newItem": syntax error
Error: near line 32: near "newItem": syntax error
Error: near line 33: near "if": syntax error
Error: near line 36: near "tail": syntax error
Error: near line 37: near "return": syntax error
Error: near line 38: unrecognized token: "}"
Error: near line 41: near "tail": syntax error
Error: near line 42: near "tail": syntax error
Error: near line 43: unrecognized token: "}"
Error: near line 47: near "struct": syntax error
Error: near line 48: near "while": syntax error
Error: near line 51: near "cur": syntax error
Error: near line 52: unrecognized token: "}"
Error: near line 57: near "if": syntax error
Error: near line 58: near "cur": syntax error
Error: near line 59: near "head": syntax error
Error: near line 61: near "if": syntax error
Error: near line 63: near "int": syntax error
Error: near line 64: near "free": syntax error
Error: near line 65: near "return": syntax error
Error: near line 66: unrecognized token: "}"
Error: near line 70: near "node": syntax error
Error: near line 72: near "public": syntax error
Error: near line 75: near "rear": syntax error
Error: near line 76: unrecognized token: "}"
Error: near line 81: near "newItem": syntax error
Error: near line 82: near "newItem": syntax error
Error: near line 83: near "newItem": syntax error
Error: near line 84: near "if": syntax error
Error: near line 87: near "rear": syntax error
Error: near line 88: near "return": syntax error
Error: near line 89: unrecognized token: "}"
Error: near line 92: near "rear": syntax error
Error: near line 93: near "rear": syntax error
Error: near line 94: unrecognized token: "}"
Error: near line 98: near "if": syntax error
Error: near line 99: near "cur": syntax error
Error: near line 100: near "front": syntax error
Error: near line 102: near "if": syntax error
Error: near line 104: near "int": syntax error
Error: near line 105: near "free": syntax error
Error: near line 106: near "return": syntax error
Error: near line 107: unrecognized token: "}"
Error: near line 111: near "int": syntax error
Error: near line 113: near "q": syntax error
Error: near line 114: near "q": syntax error
Error: near line 115: near "q": syntax error
Error: near line 117: near "cout": syntax error
Error: near line 118: near "cout": syntax error
Error: near line 119: near "cout": syntax error
Error: near line 120: near "cout": syntax error
Error: near line 121: unrecognized token: "}"
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language:
SQLite (sqlite 3.27.2)
created:
1 day ago
visibility:
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