# Check if an array is sorted or not using recursive approach!

### **Problem Statement:**

You will have given an array. You need to find out if the array is sorted in ascending order or not. Remember equal values are allowed.

### **Approach:**

Let's follow the below algorithm:

* `If the length of the array is 0 or 1, return true. (Base Condition)`
    
* `Check if the last two values of the array are sorted. Make a recursive call with a decrement in the length of the array. If values are not sorted return false.`
    
* `If all values will be sorted, then the length of the array will be 1 and the base condition will hit.`
    

### **Solution:**

The following code is in JavaScript:

```javascript

function isArraySorted(arr, n) {
	/*
	 * base case
	 * 1. if array length is (0||1) 
     * that means we don't need to validate.
	 * 2. if array already checked all values using recursive call.
	*/
	if (n == 1 || n == 0){
		return true;
	}
	
	/*
	 * 1. if first value is greater than second from last.
	 * 2. Equal values are allowed.
	*/
	if (arr[n - 1] < arr[n - 2]){
		return false;
	}
		
	/*
	 * Make recursive call
	*/
	return isArraySorted(arr, n - 1);
}

let sampleArray = [10, 20, 20, 40, 80, 90];
let length = sampleArray.length;
let ans = isArraySorted(sampleArray, length);
console.log({ ans });

console.log('--------------');

sampleArray = [10, 20, 20, 100, 80, 90];
length = sampleArray.length;
ans = isArraySorted(sampleArray, length);
console.log({ ans });
```

### **Output:**

You will able to see the following output in the console.

```bash
{ ans: true }
--------------
{ ans: false }
```

`Time Complexity: O(n)  Auxiliary Space: O(n) for Recursion Call Stack.`

Happy Codings 🧑🏼‍💻