Updated AD Lab Assignment

Third_Semester/Algorithm-Design-1(AD1)/LAB-04(Sorting)/Q3.java

@@ -1,71 +1,46 @@
 // Ques 3 : Check reverse
 
-import java.util.Scanner;
+import java.util.Arrays;
 
-public class Q3 {
-
-    public static void print(int[] arr) {
-        int n = arr.length;
-        for(int i = 0; i < n; i++) {
-            System.out.print(arr[i]+" ");
-        }
-        System.out.println();
-    }
-
-    public static void swap(int[] arr, int i, int j) {
-        int temp = arr[i];
-        arr[i] = arr[j];
-        arr[j] = temp;
-    }
-
-    public static void reverse(int[] arr, int i, int j) {
-        while(i < j) {
-            swap(arr, i, j);
-            i++;
-            j--;
+class Q3 {
+    public static boolean checkReverse(int arr[], int n) {
+        int temp[] = new int[n];
+        for (int i = 0; i < n; i++) {
+            temp[i] = arr[i];
         }
-    }
-
-    public static boolean sortedCheck(int[] arr) {
-        int flag = 0;
-        for(int i = 1; i < arr.length; i++) {
-            if(arr[i-1] > arr[i]) {
-                flag = 1;
+        Arrays.sort(temp);
+        int front;
+        for(front = 0; front < n; front++) {
+            if(temp[front] != arr[front]) {
+                break;
             }
-            return false;
         }
-        return true;
-    }
-    public static void reverseSortedCheck(int[] arr) {
-        for(int i = 0; i < arr.length; i++) {
-            for(int j = 0; j < arr.length; j++) {
-                reverse(arr, i, j);
-                boolean res = sortedCheck(arr);
-                if(res == true) {
-                    System.out.println("Reversing the Subarray : ");
-                    reverse(arr, i, j);
-                }
-                for(int k = i; k <= j; k++) {
-                    System.out.println(arr[k] + " ");
-                    System.out.println("Makes the Array Sorted!!");
-                }
-                reverse(arr, i, j);
+        int back;
+        for(back = n-1; back >= 0; back--) {
+            if(temp[back] != arr[back]) {
+                break;
             }
         }
-        System.out.println("There is no SubArray whose reversal makes the array sorted");
+        if(front >= back) {
+            return true;
+        }
+        do{
+            front++;
+            if (arr[front - 1] < arr[front]) {
+                return false;
+            }
+        } while(front != back);
+        return true;
     }
 
     public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
-        System.out.println("Enter Size of array : ");
-        int n = sc.nextInt();
-        int[] arr = new int[n];
-        System.out.println("Enter Array Elements : ");
-        for(int i = 0; i < n; i++) {
-            arr[i] = sc.nextInt();
+        int arr[] = {1, 2, 5, 4, 3};
+        int n = arr.length;
+        System.out.print("Is the Array Sorted : ");
+        if (checkReverse(arr, n)) {
+            System.out.print("True");
+        } else {
+            System.out.print("False");
         }
-        System.out.println("Array Elements are : ");
-        print(arr);
-        reverseSortedCheck(arr);
     }
 }