居中八角数字
给定一个数 n，求第 n 个位于中心的八角形数。 一个以为中心的八边形数字代表一个八边形，在连续的八边形层中，一个点在中心，其他点围绕着中心点。
例:
Input : 2
Output : 9
Input : 5
Output : 81
居中八角形第 n号由: 给出
上述方法的基本实现:
C++
// Program to find nth
// centered octagonal
// number
#include <bits/stdc++.h>
using namespace std;
// Centered octagonal number function
int cen_octagonalnum(long int n)
{
// Formula to calculate nth
// centered octagonal number &
// return it into main function.
return (4 * n * n - 4 * n + 1);
}
// Driver Code
int main()
{
long int n = 6;
cout << n << "th centered"
<< " octagonal number : ";
cout << cen_octagonalnum(n);
cout << endl;
n = 11;
cout << n << "th centered"
<< " octagonal number : ";
cout << cen_octagonalnum(n);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to find nth
// centered octagonal number
import java.io.*;
class GFG
{
// Function to find centered
// octagonal number
static int centeredoctagonalNumber(int n)
{
// Formula to calculate nth
// centered octagonal number
// and return it into main function
return 4 * n * (n - 1) + 1;
}
// Driver Code
public static void main(String args[])
{
int n = 6;
System.out.print(n + "th centered " +
"octagonal number: ");
System.out.println(
centeredoctagonalNumber(n));
n = 11;
System.out.print(n + "th centered " +
"octagonal number: ");
System.out.println(
centeredoctagonalNumber(n));
}
}
// This code has been contributed by Prasad_Kshirsagar.
Python 3
# Program to find nth
# centered octagonal number
def cen_octagonalnum(n) :
# Formula to calculate nth
# centered octagonal number
return (4 * n * n -
4 * n + 1)
# Driver Code
if __name__ == '__main__' :
n = 6
print(n,"th Centered",
"octagonal number: ",
cen_octagonalnum(n))
n = 11
print(n,"th Centered" ,
"octagonal number: ",
cen_octagonalnum(n))
# This code is contributed
# by akt_mit
C
// Program to find nth centered octagonal
// number
using System;
public class GFG{
// Centered octagonal number function
static long cen_octagonalnum(long n)
{
// Formula to calculate nth
// centered octagonal number &
// return it into main function.
return (4 * n * n - 4 * n + 1);
}
// Driver code
static public void Main ()
{
long n = 6;
Console.WriteLine(n + "th centered"
+ " octagonal number : "
+ cen_octagonalnum(n));
n = 11;
Console.WriteLine(n + "th centered"
+ " octagonal number : "
+ cen_octagonalnum(n));
}
}
// This code is contributed by anuj_67.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// Program to find nth
// centered octagonal
// number
// Centered octagonal
// number function
function cen_octagonalnum($n)
{
// Formula to calculate nth
// centered octagonal number &
// return it into main function.
return (4 * $n * $n -
4 * $n + 1);
}
// Driver Code
$n = 6;
echo $n ,"th centered",
" octagonal number : ";
echo cen_octagonalnum($n);
echo "\n";
$n = 11;
echo $n , "th centered",
" octagonal number : ";
echo cen_octagonalnum($n);
// This code is contributed by ajit
?>
java 描述语言
<script>
// Javascript Program to find nth
// centered octagonal number
// Function to find centered
// octagonal number
function centeredoctagonalNumber(n)
{
// Formula to calculate nth
// centered octagonal number
// and return it into main function
return 4 * n * (n - 1) + 1;
}
// Driver Code
var n = 6;
document.write(n + "th centered " +
"octagonal number: ");
document.write(centeredoctagonalNumber(n) + "<br>");
n = 11;
document.write(n + "th centered " +
"octagonal number: ");
document.write(centeredoctagonalNumber(n));
// This code is contributed by Kirti
</script>
输出
6th centered octagonal number : 121
11th centered octagonal number : 441
时间复杂度:O(1) T3】辅助空间: O(1)
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