Merge pull request #2 from hackerearthclub/master

Added queue,circuar queue, quick sort

Queue/CircularQueue.c

@@ -0,0 +1,99 @@
+#include <stdio.h>
+
+#define SIZE 5
+
+int items[SIZE];
+int front = -1, rear =-1;
+
+int isFull()
+{
+    if( (front == rear + 1) || (front == 0 && rear == SIZE-1)) return 1;
+    return 0;
+}
+
+int isEmpty()
+{
+    if(front == -1) return 1;
+    return 0;
+}
+
+void enQueue(int element)
+{
+    if(isFull()) printf("\n Queue is full!! \n");
+    else
+    {
+        if(front == -1) front = 0;
+        rear = (rear + 1) % SIZE;
+        items[rear] = element;
+        printf("\n Inserted -> %d", element);
+    }
+}
+
+
+int deQueue()
+{
+    int element;
+    if(isEmpty()) {
+        printf("\n Queue is empty !! \n");
+        return(-1);
+    } else {
+        element = items[front];
+        if (front == rear){
+            front = -1;
+            rear = -1;
+        } /* Q has only one element, so we reset the queue after dequeing it. ? */
+        else {
+            front = (front + 1) % SIZE;
+
+        }
+        printf("\n Deleted element -> %d \n", element);
+        return(element);
+    }
+}
+
+
+
+
+void display()
+{
+    int i;
+    if(isEmpty()) printf(" \n Empty Queue\n");
+    else
+    {
+        printf("\n Front -> %d ",front);
+        printf("\n Items -> ");
+        for( i = front; i!=rear; i=(i+1)%SIZE) {
+            printf("%d ",items[i]);
+        }
+        printf("%d ",items[i]);
+        printf("\n Rear -> %d \n",rear);
+    }
+}
+
+int main()
+{
+    // Fails because front = -1
+    deQueue();
+
+    enQueue(1);
+    enQueue(2);
+    enQueue(3);
+    enQueue(4);
+    enQueue(5);
+
+    // Fails to enqueue because front == 0 && rear == SIZE - 1
+    enQueue(6);
+
+    display();
+    deQueue();
+
+    display();
+
+    enQueue(7);
+    display();
+
+    // Fails to enqueue because front == rear + 1
+    enQueue(8);
+
+    return 0;
+}

Queue/Queue.c

@@ -0,0 +1,85 @@
+#include <stdio.h> 
+#include <stdlib.h> 
+#include <limits.h> 
+
+
+struct Queue 
+{ 
+    int front, rear, size; 
+    unsigned capacity; 
+    int* array; 
+}; 
+
+
+struct Queue* createQueue(unsigned capacity) 
+{ 
+    struct Queue* queue = (struct Queue*) malloc(sizeof(struct Queue)); 
+    queue->capacity = capacity; 
+    queue->front = queue->size = 0;  
+    queue->rear = capacity - 1;   
+    queue->array = (int*) malloc(queue->capacity * sizeof(int)); 
+    return queue; 
+} 
+
+
+int isFull(struct Queue* queue) 
+{  return (queue->size == queue->capacity);  } 
+
+
+int isEmpty(struct Queue* queue) 
+{  return (queue->size == 0); } 
+
+
+void enqueue(struct Queue* queue, int item) 
+{ 
+    if (isFull(queue)) 
+        return; 
+    queue->rear = (queue->rear + 1)%queue->capacity; 
+    queue->array[queue->rear] = item; 
+    queue->size = queue->size + 1; 
+    printf("%d enqueued to queue\n", item); 
+} 
+
+
+int dequeue(struct Queue* queue) 
+{ 
+    if (isEmpty(queue)) 
+        return INT_MIN; 
+    int item = queue->array[queue->front]; 
+    queue->front = (queue->front + 1)%queue->capacity; 
+    queue->size = queue->size - 1; 
+    return item; 
+} 
+
+// Function to get front of queue 
+int front(struct Queue* queue) 
+{ 
+    if (isEmpty(queue)) 
+        return INT_MIN; 
+    return queue->array[queue->front]; 
+} 
+
+// Function to get rear of queue 
+int rear(struct Queue* queue) 
+{ 
+    if (isEmpty(queue)) 
+        return INT_MIN; 
+    return queue->array[queue->rear]; 
+} 
+
+int main() 
+{ 
+    struct Queue* queue = createQueue(1000); 
+
+    enqueue(queue, 10); 
+    enqueue(queue, 20); 
+    enqueue(queue, 30); 
+    enqueue(queue, 40); 
+
+    printf("%d dequeued from queue\n\n", dequeue(queue)); 
+
+    printf("Front item is %d\n", front(queue)); 
+    printf("Rear item is %d\n", rear(queue)); 
+
+    return 0; 
+}

Sorting/QUICK SORT/Quicksort.c

@@ -0,0 +1,73 @@
+/* C implementation QuickSort */
+#include<stdio.h> 
+
+// A utility function to swap two elements 
+void swap(int* a, int* b) 
+{ 
+    int t = *a; 
+    *a = *b; 
+    *b = t; 
+} 
+
+/* This function takes last element as pivot, places 
+   the pivot element at its correct position in sorted 
+    array, and places all smaller (smaller than pivot) 
+   to left of pivot and all greater elements to right 
+   of pivot */
+int partition (int arr[], int low, int high) 
+{ 
+    int pivot = arr[high];    // pivot 
+    int i = (low - 1);  // Index of smaller element 
+
+    for (int j = low; j <= high- 1; j++) 
+    { 
+        // If current element is smaller than or 
+        // equal to pivot 
+        if (arr[j] <= pivot) 
+        { 
+            i++;    // increment index of smaller element 
+            swap(&arr[i], &arr[j]); 
+        } 
+    } 
+    swap(&arr[i + 1], &arr[high]); 
+    return (i + 1); 
+} 
+
+/* The main function that implements QuickSort 
+ arr[] --> Array to be sorted, 
+  low  --> Starting index, 
+  high  --> Ending index */
+void quickSort(int arr[], int low, int high) 
+{ 
+    if (low < high) 
+    { 
+        /* pi is partitioning index, arr[p] is now 
+           at right place */
+        int pi = partition(arr, low, high); 
+
+        // Separately sort elements before 
+        // partition and after partition 
+        quickSort(arr, low, pi - 1); 
+        quickSort(arr, pi + 1, high); 
+    } 
+} 
+
+/* Function to print an array */
+void printArray(int arr[], int size) 
+{ 
+    int i; 
+    for (i=0; i < size; i++) 
+        printf("%d ", arr[i]); 
+    printf("n"); 
+} 
+
+// Driver program to test above functions 
+int main() 
+{ 
+    int arr[] = {10, 7, 8, 9, 1, 5}; 
+    int n = sizeof(arr)/sizeof(arr[0]); 
+    quickSort(arr, 0, n-1); 
+    printf("Sorted array: n"); 
+    printArray(arr, n); 
+    return 0; 
+}