coded + unit tested

Author: Ram swaroop

src/me/ramswaroop/arrays/sorting/CheckSorted.java

@@ -0,0 +1,66 @@
+package me.ramswaroop.arrays.sorting;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 10/23/15
+ * @time: 8:30 AM
+ */
+public class CheckSorted {
+
+    /**
+     * Determines whether array {@param a} is sorted or not.
+     * Sort order can be either ascending or descending.
+     *
+     * @param a
+     * @return
+     */
+    public static boolean isSorted(int[] a) {
+
+        if (a.length == 0) return true;
+
+        int i;
+        boolean isAscending;
+
+        // go to index where you find a number different from  
+        // previous number (req. to determine sort order)
+        for (i = 1; i < a.length; i++) {
+            if (a[i] != a[i - 1]) break;
+        }
+
+        // all elements equal or only a single element
+        if (i == a.length) {
+            return true;
+        }
+
+        // determine sort order of array
+        if (a[i] > a[i - 1]) {
+            isAscending = true;
+        } else {
+            isAscending = false;
+        }
+
+        // check if appropriate sort property is hold for rest of array
+        if (isAscending) {
+            for (; i < a.length; i++) {
+                if (a[i] < a[i - 1]) return false;
+            }
+        } else {
+            for (; i < a.length; i++) {
+                if (a[i] > a[i - 1]) return false;
+            }
+        }
+
+        return true;
+    }
+
+    public static void main(String a[]) {
+        System.out.println(isSorted(new int[]{1, 2, 3, 4, 5}));
+        System.out.println(isSorted(new int[]{5, 4, 3, 2, 1}));
+        System.out.println(isSorted(new int[]{}));
+        System.out.println(isSorted(new int[]{0}));
+        System.out.println(isSorted(new int[]{0, 0, 0, 0, 0, 0}));
+        System.out.println(isSorted(new int[]{4, 7, 9, 1, 0}));
+    }
+}