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Shortest Un-ordered Subarray

An array is given of n length, and problem is that we have to find the length of shortest unordered {neither increasing nor decreasing} sub array in given array.

Examples:

Input : n = 5
        7 9 10 8 11
Output : 3
Explanation : 9 10 8 unordered sub array.

Input : n = 5
       1 2 3 4 5
Output : 0 
Explanation :  Array is in increasing order.



The idea is based on the fact that size of shortest subarray would be either 0 or 3. We have to check array element is either increasing or decreasing, if all array elements are in increasing or decreasing, then length of shortest sub array is 0, And if either the array element is not follow the increasing or decreasing then it shortest length is 3.

C++

// CPP program to find shortest subarray which is
// unsorted.
#include <bits/stdc++.h>
using namespace std;
  
// bool function for checking an array elements 
// are in increasing.
bool increasing(int a[], int n)
{
    for (int i = 0; i < n - 1; i++) 
        if (a[i] >= a[i + 1])
            return false;    
    return true;
}
  
// bool function for checking an array 
// elements are in decreasing.
bool decreasing(int a[], int n)
{
    for (int i = 0; i < n - 1; i++) 
        if (a[i] < a[i + 1])
            return false;    
    return true;
}
  
int shortestUnsorted(int a[], int n)
{
    // increasing and decreasing are two functions.
    // if function return true value then print
    // 0 otherwise 3.
    if (increasing(a, n) == true ||
       decreasing(a, n) == true)
        return 0;
    else
        return 3;
}
  
// Driver code
int main()
{
    int ar[] = { 7, 9, 10, 8, 11 };
    int n = sizeof(ar) / sizeof(ar[0]);
    cout << shortestUnsorted(ar, n);
    return 0;
}

Java

// JAVA program to find shortest subarray which is
// unsorted.
import java.util.*;
import java.io.*;
  
class GFG {
      
    // boolean function to check array elements 
    // are in increasing order or not
    public static boolean increasing(int a[],int n)
    {
        for (int i = 0; i < n - 1; i++) 
            if (a[i] >= a[i + 1])
                return false
                  
        return true;
    }
      
    // boolean function to check array elements 
    // are in decreasing order or not
    public static boolean decreasing(int arr[],int n)
    {
        for (int i = 0; i < n - 1; i++) 
            if (arr[i] < arr[i + 1])
                return false
                  
        return true;
    }
      
    public static int shortestUnsorted(int a[],int n)
    {
          
        // increasing and decreasing are two functions.
        // if function return true value then print
        // 0 otherwise 3.
        if (increasing(a, n) == true || 
                             decreasing(a, n) == true)
            return 0;
        else
            return 3;
    }
      
    // driver program
    public static void main (String[] args) {
          
        int ar[] = new int[]{7, 9, 10, 8, 11};
        int n = ar.length;
          
        System.out.println(shortestUnsorted(ar,n));
    }
}
  
// This code is contributed by Akash Singh.

Python3

# Python3 program to find shortest 
# subarray which is unsorted
  
# Bool function for checking an array  
# elements are in increasing
def increasing(a, n):
  
    for i in range(0, n - 1): 
        if (a[i] >= a[i + 1]):
            return False
              
    return True
  
# Bool function for checking an array 
# elements are in decreasing
def decreasing(a, n):
  
    for i in range(0, n - 1): 
        if (a[i] < a[i + 1]):
            return False
              
    return True
  
def shortestUnsorted(a, n):
  
    # increasing and decreasing are two functions.
    # if function return True value then print
    # 0 otherwise 3.
    if (increasing(a, n) == True or
        decreasing(a, n) == True):
        return 0
    else:
        return 3
  
# Driver code
ar = [7, 9, 10, 8, 11
n = len(ar) 
print(shortestUnsorted(ar, n))
  
# This code is contributed by Smitha Dinesh Semwal. 

C#

// Program to find the shortest
// subarray which is unsorted.
using System;
  
class GFG {
  
    // boolean function to check
    // array elements are in the
    // increasing order or not
    public static bool increasing(int[] a, int n)
    {
        for (int i = 0; i < n - 1; i++)
            if (a[i] >= a[i + 1])
                return false;
  
        return true;
    }
  
    // boolean function to check
    // array elements are in the
    // decreasing order or not
    public static bool decreasing(int[] arr, int n)
    {
        for (int i = 0; i < n - 1; i++)
            if (arr[i] < arr[i + 1])
                return false;
  
        return true;
    }
  
    public static int shortestUnsorted(int[] a, int n)
    {
  
        // increasing and decreasing are
        // two functions. function return
        // true value then print 0 else 3
         if (increasing(a, n) == true ||
             decreasing(a, n) == true)
            return 0;
        else
            return 3;
    }
  
    // Driver program
    public static void Main()
    {
  
        int[] ar = new int[] { 7, 9, 10, 8, 11 };
        int n = ar.Length;
        Console.WriteLine(shortestUnsorted(ar, n));
    }
}
  
// This code is contributed by vt_m.

PHP

<?php
// php program to find shortest 
// subarray which is unsorted.
  
// bool function for checking an 
// array elements are in increasing.
function increasing($a, $n)
{
    for ( $i = 0; $i < $n - 1; $i++) 
        if ($a[$i] >= $a[$i + 1])
            return false;
              
    return true;
}
  
// bool function for checking an 
// array elements are in decreasing.
function decreasing($a, $n)
{
    for ($i = 0; $i < $n - 1; $i++) 
        if ($a[$i] < $a[$i + 1])
            return false; 
    return true;
}
  
function shortestUnsorted($a, $n)
{
      
    // increasing and decreasing are
    // two functions. if function 
    // return true value then print
    // 0 otherwise 3.
    if (increasing($a, $n) == true ||
          decreasing($a, $n) == true)
        return 0;
    else
        return 3;
}
  
// Driver code
$ar = array( 7, 9, 10, 8, 11 );
$n = sizeof($ar);
echo shortestUnsorted($ar, $n);
  
// This code is contributed by
// nitin mittal.
?>

Output :

3


This article is attributed to GeeksforGeeks.org

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