C++ determine size of array

The title might seem it’s a duplicate question. Not sure if it actually is.
Consider the code below:
# include <iostream>

size_t arrSize(const int* arr)
return *(&arr+1)-arr;

void foo(int* arr)
std::cout << …

spam title removed [closed]

You are given an array prices where prices[i] is the price of a given stock on the ith day.
You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.
Return th…