程序检查N是否为居中立方数

给定数字N ，任务是检查N是否为中心立方数。

A centred cubic number counts the number of points which are formed by a point that is surrounded by concentric cubical layers in 3D with i² points on the square faces of the i-th layer. The first few Centered cube numbers are 1, 9, 35, 91, 189, 341, 559, 855 … 
 

例子：

Input: N = 9 
Output: Yes 
Explanation: 
9 is the second Centered cube number
Input: N = 6 
Output: No 
 

方法：想法是从一个迭代开始，并检查第i^个项是否等于N。

1. 中心立方数的第N^个项由下式给出$(2 * N + 1) * ( N^2 + N + 1)$ 。
2. 从1开始运行循环，以找到^第i^个居中的立方体编号。
3. 检查第i个项是否等于N。如果相等，则返回true。
4. 如果第i个项大于N，则返回false。

下面是上述方法的实现：

C++

// C++ program to check if N
// is a centered cubic number
#include 
using namespace std;
 
// Function to check if the number N
// is a centered cubic number
bool isCenteredcube(int N)
{
// Iterating from 1
    int i = 1;
 
// Infinite loop
    while (true) {
 
        // Finding ith_term
        int ith_term = (2 * i + 1)
* (i * i + i + 1);
 
        // Checking if the number N
        // is a Centered cube number
        if (ith_term == N) {
            return true;
        }
 
        // If ith_term > N then
        // N is not a Centered cube number
        if (ith_term > N) {
            return false;
        }
 
        // Incrementing i
        i++;
    }
}
 
// Driver code
int main()
{
    int N = 9;
 
    // Function call
    if (isCenteredcube(N)) {
        cout << "Yes";
    }
    else {
        cout << "No";
    }
    return 0;
}

Java

// Java program to check if N
// is a centered cubic number
class GFG{
 
// Function to check if N
// is a centered cubic number
static boolean isCenteredcube(int N)
{
     
    // Iterating from 1
    int i = 1;
     
    // Infinite loop
    while (true)
    {
         
        // Finding ith_term
        int ith_term = (2 * i + 1) *
                       (i * i + i + 1);
 
        // Checking if the number N
        // is a centered cube number
        if (ith_term == N)
        {
            return true;
        }
 
        // If ith_term > N then N is 
        // not a centered cube number
        if (ith_term > N)
        {
            return false;
        }
 
        // Incrementing i
        i++;
    }
}
 
// Driver code
public static void main(String[] args)
{
    int N = 9;
 
    // Function call
    if (isCenteredcube(N))
    {
        System.out.println("Yes");
    }
    else
    {
        System.out.println("No");
    }
}
}
 
// This code is contributed by shubham

Python3

# Python3 program to check if N
# is a centered cubic number
 
# Function to check if N
# is a centered cubic number
def isCenteredcube(N):
 
    # Iterating from 1
    i = 1;
     
    # Infinite loop
    while (True):
     
        # Finding ith_term
        ith_term = ((2 * i + 1) *
                    (i * i + i + 1));
 
        # Checking if the number N
        # is a centered cube number
        if (ith_term == N):
            return True;
         
        # If ith_term > N then N is
        # not a centered cube number
        if (ith_term > N):
            return False;
         
        # Incrementing i
        i += 1;
     
# Driver code
N = 9;
 
# Function call
if (isCenteredcube(N)):
    print("Yes");
else:
    print("No");
 
# This code is contributed by Code_Mech

C#

// C# program to check if N
// is a centered cubic number
using System;
class GFG{
 
// Function to check if N
// is a centered cubic number
static Boolean isCenteredcube(int N)
{
     
    // Iterating from 1
    int i = 1;
     
    // Infinite loop
    while (true)
    {
         
        // Finding ith_term
        int ith_term = (2 * i + 1) *
                       (i * i + i + 1);
 
        // Checking if the number N
        // is a centered cube number
        if (ith_term == N)
        {
            return true;
        }
 
        // If ith_term > N then N is
        // not a centered cube number
        if (ith_term > N)
        {
            return false;
        }
 
        // Incrementing i
        i++;
    }
}
 
// Driver code
public static void Main()
{
    int N = 9;
     
    // Function call
    if (isCenteredcube(N))
    {
        Console.WriteLine("Yes");
    }
    else
    {
        Console.WriteLine("No");
    }
}
}
 
// This code is contributed by shivanisinghss2110

Javascript

    // Javascript program to check if N 
    // is a centered cubic number
     
    // Function to check if the number N
    // is a centered cubic number
    function isCenteredcube(N)
    {
        // Iterating from 1
        let i = 1;
 
        // Infinite loop
        while (true) {
 
            // Finding ith_term
            let ith_term = (2 * i + 1) * (i * i + i + 1);
 
            // Checking if the number N
            // is a Centered cube number
            if (ith_term == N) {
                return true;
            }
 
            // If ith_term > N then
            // N is not a Centered cube number
            if (ith_term > N) {
                return false;
            }
 
            // Incrementing i
            i++;
        }
    }
     
    let N = 9;
   
    // Function call
    if (isCenteredcube(N)) {
        document.write("Yes");
    }
    else {
        document.write("No");
    }
 
    // This code is contributed by divyesh072019.

输出：

Yes

时间复杂度： O(N)。