检查数组是否表示二进制搜索树的顺序

给定一个N元素数组。任务是检查它是否是任何二进制搜索树的有序遍历。如果是二进制搜索树的有序遍历，则打印“是”，否则打印“否”。

例子：

Input : arr[] = { 19, 23, 25, 30, 45 }
Output : Yes

Input : arr[] = { 19, 23, 30, 25, 45 }
Output : No

想法是利用对二进制搜索树的有序遍历进行排序的事实。因此，只需检查给定数组是否已排序。

C++

// C++ program to check if a given array is sorted
// or not.
#include
using namespace std;
  
// Function that returns true if array is Inorder
// traversal of any Binary Search Tree or not.
bool isInorder(int arr[], int n)
{
    // Array has one or no element
    if (n == 0 || n == 1)
        return true;
  
    for (int i = 1; i < n; i++)
  
        // Unsorted pair found
        if (arr[i-1] > arr[i])
            return false;
  
    // No unsorted pair found
    return true;
}
  
// Driver code
int main()
{
    int arr[] = { 19, 23, 25, 30, 45 };
    int n = sizeof(arr)/sizeof(arr[0]);
      
    if (isInorder(arr, n))
        cout << "Yesn";
    else
        cout << "Non";
          
  return 0;
}

Java

// Java program to check if a given array is sorted 
// or not. 
  
class GFG {
  
// Function that returns true if array is Inorder 
// traversal of any Binary Search Tree or not. 
    static boolean isInorder(int[] arr, int n) {
        // Array has one or no element 
        if (n == 0 || n == 1) {
            return true;
        }
  
        for (int i = 1; i < n; i++) // Unsorted pair found 
        {
            if (arr[i - 1] > arr[i]) {
                return false;
            }
        }
  
        // No unsorted pair found 
        return true;
    }
// Drivers code 
  
    public static void main(String[] args) {
        int arr[] = {19, 23, 25, 30, 45};
        int n = arr.length;
        if (isInorder(arr, n)) {
            System.out.println("Yes");
        } else {
            System.out.println("Non");
        }
    }
}
//This code is contributed by 29AjayKumar

Python3

# Python 3 program to check if a given array 
# is sorted or not.
  
# Function that returns true if array is Inorder
# traversal of any Binary Search Tree or not.
def isInorder(arr, n):
      
    # Array has one or no element
    if (n == 0 or n == 1):
        return True
  
    for i in range(1, n, 1):
          
        # Unsorted pair found
        if (arr[i - 1] > arr[i]):
            return False
  
    # No unsorted pair found
    return True
  
# Driver code
if __name__ == '__main__':
    arr = [19, 23, 25, 30, 45]
    n = len(arr)
      
    if (isInorder(arr, n)):
        print("Yes")
    else:
        print("No")
          
# This code is contributed by
# Sahil_Shelangia

C#

// C# program to check if a given 
// array is sorted or not. 
using System;
  
class GFG
{
  
// Function that returns true if 
// array is Inorder traversal of 
// any Binary Search Tree or not. 
static bool isInorder(int[] arr, int n)
{
    // Array has one or no element 
    if (n == 0 || n == 1) 
    {
        return true;
    }
      
    // Unsorted pair found 
    for (int i = 1; i < n; i++) 
    {
        if (arr[i - 1] > arr[i])
        {
            return false;
        }
    }
  
    // No unsorted pair found 
    return true;
}
  
// Driver code 
public static void Main() 
{
    int []arr = {19, 23, 25, 30, 45};
    int n = arr.Length;
    if (isInorder(arr, n)) 
    {
        Console.Write("Yes");
    } 
    else
    {
        Console.Write("Non");
    }
}
}
  
// This code is contributed by Rajput-Ji

PHP

 $arr[$i])
            return false;
  
    // No unsorted pair found
    return true;
}
  
// Driver code
$arr = array(19, 23, 25, 30, 45);
$n = sizeof($arr);
  
if (isInorder($arr, $n))
    echo "Yes";
else
    echo "No";
  
// This code is contributed
// by Akanksha Rai
?>

输出：

Yes