Given an array arr[] of size N, the task is to check if the array is spirally sorted or not. If found to be true, then print "YES". Otherwise, print "NO".
Note: An array is spirally sorted if arr[0] ? arr[N - 1] ? arr[1] ? arr[N - 2] ...
Examples:
Input: arr[] = { 1, 10, 14, 20, 18, 12, 5 }
Output: YES
Explanation:
arr[0] < arr[6]
arr[1] < arr[5]
arr[2] < arr[4]
Therefore, the required output is YES.Input: arr[] = { 1, 2, 4, 3 }
Output: NO
Approach: The idea is to traverse the array and for every array element, say arr[i], check if arr[i] is less than or equal to arr[N - i - 1] and arr[N - i - 1] less than or equal to arr[i + 1] or not. If found to be false, then print "NO". Otherwise, if all array elements satisfy the condition, then print "YES". Follow the steps below to solve the problem:
- Initialize two variables, say start and end, to store the start and end indices of the given array.
- Iterate a loop while start is less than end, and check if arr[start] less than or equal to arr[end] and arr[end] is less than or equal to arr[start + 1] or not. If found to be false, then print "NO".
- Otherwise, print "YES".
Below is the implementation of the above approach:
// C++ program to implement
// the above approach
#include <iostream>
using namespace std;
// Function to check if the array is
// spirally sorted or not
bool isSpiralSorted(int arr[], int n)
{
// Stores start index
// of the array
int start = 0;
// Stores end index
// of an array
int end = n - 1;
while (start < end) {
// If arr[start]
// greater than arr[end]
if (arr[start] > arr[end]) {
return false;
}
// Update start
start++;
// If arr[end]
// greater than arr[start]
if (arr[end] > arr[start]) {
return false;
}
// Update end
end--;
}
return true;
}
// Driver Code
int main()
{
int arr[] = { 1, 10, 14, 20, 18, 12, 5 };
int N = sizeof(arr) / sizeof(arr[0]);
// Function Call
if (isSpiralSorted(arr, N))
cout << "YES" << endl;
else
cout << "NO" << endl;
return 0;
}
// Java program to implement
// the above approach
import java.util.*;
class GFG{
// Function to check if the array is
// spirally sorted or not
static boolean isSpiralSorted(int[] arr, int n)
{
// Stores start index
// of the array
int start = 0;
// Stores end index
// of an array
int end = n - 1;
while (start < end)
{
// If arr[start]
// greater than arr[end]
if (arr[start] > arr[end])
{
return false;
}
// Update start
start++;
// If arr[end]
// greater than arr[start]
if (arr[end] > arr[start])
{
return false;
}
// Update end
end--;
}
return true;
}
// Driver code
public static void main(String[] args)
{
int[] arr = { 1, 10, 14, 20, 18, 12, 5 };
int N = arr.length;
// Function Call
if (isSpiralSorted(arr, N) != false)
System.out.print("YES");
else
System.out.print("NO");
}
}
// This code is contributed by sanjoy_62
# Python3 program to implement
# the above approach
# Function to check if the array is
# spirally sorted or not
def isSpiralSorted(arr, n) :
# Stores start index
# of the array
start = 0;
# Stores end index
# of an array
end = n - 1;
while (start < end) :
# If arr[start]
# greater than arr[end]
if (arr[start] > arr[end]) :
return False;
# Update start
start += 1;
# If arr[end]
# greater than arr[start]
if (arr[end] > arr[start]) :
return False;
# Update end
end -= 1;
return True;
# Driver Code
if __name__ == "__main__" :
arr = [ 1, 10, 14, 20, 18, 12, 5 ];
N = len(arr);
# Function Call
if (isSpiralSorted(arr, N)) :
print("YES");
else :
print("NO");
# This code is contributed by AnkThon
// C# program to implement
// the above approach
using System;
using System.Collections.Generic;
class GFG
{
// Function to check if the array is
// spirally sorted or not
static bool isSpiralSorted(int[] arr, int n)
{
// Stores start index
// of the array
int start = 0;
// Stores end index
// of an array
int end = n - 1;
while (start < end)
{
// If arr[start]
// greater than arr[end]
if (arr[start] > arr[end])
{
return false;
}
// Update start
start++;
// If arr[end]
// greater than arr[start]
if (arr[end] > arr[start])
{
return false;
}
// Update end
end--;
}
return true;
}
// Driver code
static void Main()
{
int[] arr = { 1, 10, 14, 20, 18, 12, 5 };
int N = arr.Length;
// Function Call
if (isSpiralSorted(arr, N))
Console.WriteLine("YES");
else
Console.WriteLine("NO");
}
}
// This code is contributed bydivyesh072019
<script>
// Javascript program to implement
// the above approach
// Function to check if the array is
// spirally sorted or not
function isSpiralSorted(arr, n)
{
// Stores start index
// of the array
let start = 0;
// Stores end index
// of an array
let end = n - 1;
while (start < end)
{
// If arr[start]
// greater than arr[end]
if (arr[start] > arr[end])
{
return false;
}
// Update start
start++;
// If arr[end]
// greater than arr[start]
if (arr[end] > arr[start])
{
return false;
}
// Update end
end--;
}
return true;
}
let arr = [ 1, 10, 14, 20, 18, 12, 5 ];
let N = arr.length;
// Function Call
if (isSpiralSorted(arr, N))
document.write("YES");
else
document.write("NO");
</script>
Output:
YES
Time Complexity: O(N)
Auxiliary Space: O(1)
