Merge pull request ShreyaDhir#164 from Shreya2221/master

Ascending priority queue

Ascending_priority_queue.c

@@ -0,0 +1,141 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAX 5
+
+void insert_by_priority(int);
+void delete_by_priority(int);
+void create();
+void check(int);
+void display_pqueue();
+
+int pri_que[MAX];
+int front, rear;
+
+void main()
+{
+    int n, ch;
+
+    printf("\n1 - Insert an element into queue");
+    printf("\n2 - Delete an element from queue");
+    printf("\n3 - Display queue elements");
+    printf("\n4 - Exit");
+
+    create();
+
+    while (1)
+    {
+        printf("\nEnter your choice : ");    
+        scanf("%d", &ch);
+
+        switch (ch)
+        {
+        case 1: 
+            printf("\nEnter value to be inserted : ");
+            scanf("%d",&n);
+            insert_by_priority(n);
+            break;
+        case 2:
+            printf("\nEnter value to delete : ");
+            scanf("%d",&n);
+            delete_by_priority(n);
+            break;
+        case 3: 
+            display_pqueue();
+            break;
+        case 4: 
+            exit(0);
+        default: 
+            printf("\nChoice is incorrect, Enter a correct choice");
+        }
+    }
+}
+
+void create()
+{
+    front = rear = -1;
+}
+
+void insert_by_priority(int data)
+{
+    if (rear >= MAX - 1)
+    {
+        printf("\nQueue overflow no more elements can be inserted");
+        return;
+    }
+    if ((front == -1) && (rear == -1))
+    {
+        front++;
+        rear++;
+        pri_que[rear] = data;
+        return;
+    }    
+    else
+        check(data);
+    rear++;
+}
+
+void check(int data)
+{
+    int i,j;
+
+    for (i = 0; i <= rear; i++)
+    {
+        if (data >= pri_que[i])
+        {
+            for (j = rear + 1; j > i; j--)
+            {
+                pri_que[j] = pri_que[j - 1];
+            }
+            pri_que[i] = data;
+            return;
+        }
+    }
+    pri_que[i] = data;
+}
+
+void delete_by_priority(int data)
+{
+    int i;
+
+    if ((front==-1) && (rear==-1))
+    {
+        printf("\nQueue is empty no elements to delete");
+        return;
+    }
+
+    for (i = 0; i <= rear; i++)
+    {
+        if (data == pri_que[i])
+        {
+            for (; i < rear; i++)
+            {
+                pri_que[i] = pri_que[i + 1];
+            }
+
+        pri_que[i] = -99;
+        rear--;
+
+        if (rear == -1) 
+            front = -1;
+        return;
+        }
+    }
+    printf("\n%d not found in queue to delete", data);
+}
+
+void display_pqueue()
+{
+    if ((front == -1) && (rear == -1))
+    {
+        printf("\nQueue is empty");
+        return;
+    }
+
+    for (; front <= rear; front++)
+    {
+        printf(" %d ", pri_que[front]);
+    }
+
+    front = 0;
+}