Extreme values - return index and pointer, C++ (gcc)

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#include <iostream>
#include <string>
using namespace std;

// Returns the index of the smallest value
// -1 if not found
int smallest(const double a[], size_t len)
{
    int result = -1; // not found
    if (len > 0)
    {
        int smallest = a[0];
        result = 0;
        for (size_t i = 1; i < len; ++i)
        {
            if (a[i] < smallest)
            {
                result = i;
                smallest = a[i];
            }
        }
    }
    return result;
}

// Returns a pointer to largest value
// nullptr if not found
const double* biggest(const double a[], size_t len)
{
    if (len == 0) return nullptr;
    
    const double* p = a;
    double largest = *p;
    for (size_t i = 1; i < len; ++i)
    {
        if (a[i] > largest)
        {
            p = &a[i];
            largest = a[i];
        }
    }
    return p;
}

int main()
{
    double a[] = {1.5, 2.5, 3.5, 2.75, 1.75};
    auto little = a[smallest(a, 5)]; // returns index if found
    auto big = *biggest(a, 5); // returns pointer if found
    
    cout << "smallest->" << little << ", biggest->" << big << endl;
    return 0;
}

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Compilation time: 0.53 sec, absolute running time: 0.16 sec, cpu time: 0.01 sec, memory peak: 5 Mb, absolute service time: 0,82 sec