给定大小为N的数组arr [] ，其中包含至少一个复合数字。任务是找出数组中所有处于奇数索引(其中索引基于1)的复合数字的总和。
例子：
Input: arr = [13, 5, 8, 16, 25]
Output: 33
Explanation:
The number in the odd indices are 13, 8, 25 since we follow 1 based indexing.
Out of all these 3 numbers, the composite numbers are 8 and 25, which sums to 33.
Input: arr = [9, 7, 14, 10, 34]
Output: 57
Explanation:
The number in the odd indices are 9, 14, 34 since we follow 1 based indexing.
All three numbers are composite numbers, which sums to 57.
方法：
为了解决上述问题，主要思想是检查复合数字，即，如果整数有两个以上的因子，则它是一个复合数字，否则就没有。然后，我们将迭代并检查数组的奇数索引中的复合数。如果它是一个复合数，则将其添加到sum变量中，否则将其跳过，直到到达数组末尾为止。
下面是上述方法的实现：
C++
// C++ implementation to find the sum of all the
// composite numbers from odd indices of the given array
#include
using namespace std;
// Function to check for composite numbers
int composite(int n){
int flag = 0;
int c = 0;
// Check if the factors are greater than 2
for (int j = 1; j <= n; j++){
if (n % j == 0){
c += 1;
}
}
// Check if the number is composite or not
if (c >= 3)
flag = 1;
return flag;
}
// Function to print the sum of all
// composite numbers in the array
void odd_indices(int arr[],int n){
int sum = 0;
// Iterate for odd indices in the array
for (int k = 0; k < n; k += 2){
int check = composite(arr[k]);
// Check if the number is composite
// then add it to sum
if (check == 1)
sum += arr[k];
}
// return the sum
cout << sum << endl;
}
// Driver code
int main(){
int arr[] = {13, 5, 8, 16, 25};
int n = sizeof(arr)/sizeof(arr[0]);
odd_indices(arr,n);
}
// This code is contributed by Surendra_Gangwar Java
// Java implementation to find the sum of all the
// composite numbers from odd indices of the given array
class GFG{
// Function to check for composite numbers
static int composite(int n){
int flag = 0;
int c = 0;
// Check if the factors are greater than 2
for (int j = 1; j <= n; j++){
if (n % j == 0){
c += 1;
}
}
// Check if the number is composite or not
if (c >= 3)
flag = 1;
return flag;
}
// Function to print the sum of all
// composite numbers in the array
static void odd_indices(int arr[],int n){
int sum = 0;
// Iterate for odd indices in the array
for (int k = 0; k < n; k += 2){
int check = composite(arr[k]);
// Check if the number is composite
// then add it to sum
if (check == 1)
sum += arr[k];
}
// return the sum
System.out.print(sum +"\n");
}
// Driver code
public static void main(String[] args){
int arr[] = {13, 5, 8, 16, 25};
int n = arr.length;
odd_indices(arr,n);
}
}
// This code contributed by sapnasingh4991Python3
# Python3 implementation to find the sum of all the
# composite numbers from odd indices of the given array
# Function to print the sum of all
# composite numbers in the array
def odd_indices(arr):
sum = 0
# Iterate for odd indices in the array
for k in range (0, len(arr), 2):
check = composite (arr[k])
# Check if the number is composite
# then add it to sum
sum += arr[k] if check == 1 else 0
# return the sum
print (sum)
# Function to check for composite numbers
def composite(n):
flag = 0
c = 0
# Check if the factors are greater than 2
for j in range (1, n + 1):
if (n % j == 0):
c += 1
# Check if the number is composite or not
if (c >= 3):
flag = 1
return flag
# Driver code
if __name__ == "__main__":
arr = [13, 5, 8, 16, 25]
odd_indices(arr)C#
// C# implementation to find the sum
// of all the composite numbers from
// odd indices of the given array
using System;
class GFG{
// Function to check for composite numbers
static int composite(int n)
{
int flag = 0;
int c = 0;
// Check if the factors are greater than 2
for(int j = 1; j <= n; j++)
{
if (n % j == 0)
{
c += 1;
}
}
// Check if the number is composite or not
if (c >= 3)
flag = 1;
return flag;
}
// Function to print the sum of all
// composite numbers in the array
static void odd_indices(int []arr,int n)
{
int sum = 0;
// Iterate for odd indices in the array
for(int k = 0; k < n; k += 2)
{
int check = composite(arr[k]);
// Check if the number is composite
// then add it to sum
if (check == 1)
sum += arr[k];
}
// return the sum
Console.Write(sum + "\n");
}
// Driver code
public static void Main(String[] args)
{
int []arr = { 13, 5, 8, 16, 25 };
int n = arr.Length;
odd_indices(arr, n);
}
}
// This code is contributed by Rohit_ranjan输出：
33