编写一个函数，求出一维整型数组a[n]中所有元素的平方之和（用递归方法）

Question

c++

Answer 1

#include <iostream>
using namespace std;int fun(int a[],int n)
{
if(n==0) return a[n]*a[n];
return fun(a,n-1)+a[n]*a[n];
}
int main()
{
int a[]={1,2,3,4,5};
int sum=fun(a,4);
cout<<sum<<endl;
return 0;
}

Answer 2

#include <iostream>
using namespace std;int add_power(int *a, int n) {
if (n == 1) return a[0] * a[0];
else
return a[n-1] * a[n-1] + add_power(a, n-1);
}int main() {
int a[4] = {1, 2, 3, 4}; cout << "The result is " << add_power(a, 4) << endl;
}

Answer 3

int sum=0;int a[n];for(int i=0;i<=n;i++){ sum+=a[i]*a[i]}