给定数字N,任务是找到前N个中心八角形数字的总和。
The first few Centered Octagonal numbers are 1, 9, 25, 49, 81, 121, 169, 225, 289, 361 …
例子:
Input: N = 3
Output: 35
Explanation:
1, 9 and 25 are the first three Centered Octagonal numbers.
Input: N = 5
Output: 165
方法:
- 最初,我们需要创建一个函数,该函数将帮助我们计算第N个居中的八边形数。
- 现在,运行一个从1到N的循环,以找到第i个居中的八边形数字。
- 将所有以上计算的居中八角形数字相加。
- 最后,显示前N个居中的八角形数字的总和。
下面是上述方法的实现:
C++
// C++ program to find the sum of the
// first N centered octagonal number
#include
using namespace std;
// Function to find the N-th centered
// octagonal number
int center_Octagonal_num(int n)
{
// Formula to calculate
// nth centered octagonal
// number
return (4 * n * n - 4 * n + 1);
}
// Function to find the sum of the first
// N centered octagonal numbers
int sum_center_Octagonal_num(int n)
{
// Variable to store
// the sum
int summ = 0;
// Iterating through the range
// 1 to N
for(int i = 1; i < n + 1; i++)
{
summ += center_Octagonal_num(i);
}
return summ;
}
// Driver Code
int main()
{
int n = 5;
cout << (sum_center_Octagonal_num(n));
return 0;
}
// This code is contributed by PratikBasu
Java
// Java program to find the sum of the
// first N centered octagonal number
class GFG {
// Function to find N-th centered
// octagonal number
static int center_Octagonal_num(int n)
{
// Formula to calculate
// nth centered octagonal
// number
return (4 * n * n - 4 * n + 1);
}
// Function to find the
// sum of the first N
// centered octagonal
// numbers
static int sum_center_Octagonal_num(int n)
{
// Variable to store
// the sum
int summ = 0;
// Iterating through the first N
// numbers
for(int i = 1; i < n + 1; i++)
{
summ += center_Octagonal_num(i);
}
return summ;
}
// Driver code
public static void main(String[] args)
{
int n = 5;
System.out.println(sum_center_Octagonal_num(n));
}
}
// This code is contributed by Princi Singh
Python3
# Python3 program to find the
# sum of the first N
# Centered Octagonal number
# Function to find N-th
# Centered Octagonal
# number
def center_Octagonal_num(n):
# Formula to calculate
# nth centered Octagonal
# number
return (4 * n * n - 4 * n + 1)
# Function to find the
# sum of the first N
# Centered Octagonal
# numbers
def sum_center_Octagonal_num(n) :
# Variable to store
# the sum
summ = 0
# Iterating through the first N
# numbers
for i in range(1, n + 1):
summ += center_Octagonal_num(i)
return summ
# Driver code
if __name__ == '__main__' :
n = 5
print(sum_center_Octagonal_num(n))
C#
// C# program to find the sum of the
// first N centered octagonal number
using System;
class GFG{
// Function to find N-th centered
// octagonal number
static int center_Octagonal_num(int n)
{
// Formula to calculate
// nth centered octagonal
// number
return (4 * n * n - 4 * n + 1);
}
// Function to find the sum of
// the first N centered octagonal
// numbers
static int sum_center_Octagonal_num(int n)
{
// Variable to store
// the sum
int summ = 0;
// Iterating through the first N
// numbers
for(int i = 1; i < n + 1; i++)
{
summ += center_Octagonal_num(i);
}
return summ;
}
// Driver code
public static void Main()
{
int n = 5;
Console.WriteLine(sum_center_Octagonal_num(n));
}
}
// This code is contributed by Akanksha_Rai
Javascript
// This code is contributed by divyeshrabadiya07.
输出:
165
时间复杂度: O(N)。