求第一个 N 中心八角数的和
原文:https://www . geeksforgeeks . org/find-第一个以 n 为中心的八边形数字的总和/
给定一个数 N，任务是求前 N 个居中的八边形数的和。
前几个居中的八边形数字是 1、9、25、49、81、121、169、225、289、361……
例:
输入: N = 3 输出: 35 说明: 1、9、25 是前三个居中的八角形数字。 输入: N = 5 输出: 165
进场:
- 首先，我们需要创建一个函数来帮助我们计算第 N个以八角形为中心的数字。
- 现在，运行一个从 1 到 N 的循环，找到第 I个居中的八边形数字。
- 将上面计算的所有居中的八边形数字相加。
- 最后，显示前 N 个居中的八边形数字的总和。
以下是上述方法的实现:
C++
// C++ program to find the sum of the
// first N centered octagonal number
#include<bits/stdc++.h>
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 语言(一种计算机语言，尤用于创建网站)
// 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
Python 3
# 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
java 描述语言
<script>
// Javascript program to find the sum of the
// first N centered octagonal number
// Function to find the N-th centered
// octagonal number
function 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
function sum_center_Octagonal_num(n)
{
// Variable to store
// the sum
let summ = 0;
// Iterating through the range
// 1 to N
for(let i = 1; i < n + 1; i++)
{
summ += center_Octagonal_num(i);
}
return summ;
}
let n = 5;
document.write(sum_center_Octagonal_num(n));
</script>
// This code is contributed by divyeshrabadiya07.
Output:
165
时间复杂度: O(N)。
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