Create main.cpp

Author: JawadSher

16 - Queue Data Structure Problems/01 - Linear Queue Problems/11 - Implement k Queues in an Single Array/main.cpp

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+#include <iostream>
+using namespace std;
+
+class kQueue{
+  public:
+    int *arr;
+    int k;
+    int n;
+    int *front;
+    int *rear;
+    int freeSpot;
+    int *next;
+
+    kQueue(int n, int k){
+      this -> n = n;
+      this -> k = k;
+      arr = new int[n];
+      front = new int[k];
+      rear = new int[k];
+      next = new int[n];
+      freeSpot = 0;
+
+      for(int i = 0; i < k; i++){
+        front[i] = -1;
+        rear [i] = -1;
+      }
+
+      for(int i = 0; i < n-1; i++){
+        next[i] = i + 1;
+      }
+      next[n-1] = -1;
+    }
+
+    void enQueue(int data, int qn){
+      // overflow 
+      if(freeSpot == -1){
+        cout << "No empty space is available" << endl;
+        return;
+      }
+
+      // find first free index;
+      int index = freeSpot;
+
+      // update freeSpot;
+      freeSpot = next[index];
+
+      // check wheather first element
+      if(front[qn-1] == -1){
+        front[qn-1] = index;
+      }else{
+        // link new element to the prev element
+        next[rear[qn-1]] = index;
+      }
+
+      // update next;
+      next[index] = -1;
+
+      // update rear;
+      rear[qn-1] = index;
+
+      // push element;
+      arr[index] = data;
+
+    }
+
+    int deQueue(int qn){
+      // underflow
+      if(front[qn-1] == -1){
+        cout << "Queue underflow" <<endl;
+        return -1;
+      }
+
+      // find index to pop
+      int index = front[qn-1];
+
+      // update front pointer
+      front[qn-1] = next[index];
+
+      // next freeSpot
+      next[index] = freeSpot;
+      freeSpot = index;
+
+      return arr[index];
+    }
+};
+
+int main() {
+  kQueue q(10, 3);
+
+  q.enQueue(10, 1);
+  q.enQueue(15, 1);
+  q.enQueue(20, 2);
+  q.enQueue(25, 1);
+  q.enQueue(30, 2);
+  q.enQueue(35, 3);
+
+  cout << "Element poped from q1 : " << q.deQueue(1) <<endl;
+  cout << "Element poped from q1 : " << q.deQueue(1) <<endl;
+  cout << "Element poped from q2 : " << q.deQueue(2) <<endl;
+  cout << "Element poped from q3 : " << q.deQueue(3) <<endl;
+  return 0;
+}