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++14
// C++ program to implement// the above approach#include <iostream>using namespace std;// Function to check if the array is// spirally sorted or notbool 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 Codeint 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
// 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
# Python3 program to implement# the above approach# Function to check if the array is# spirally sorted or notdef 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 Codeif __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#
// 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 |
Javascript
<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)
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