Quick coding challenge - given an array of numbers let i the current element, calculate x as the difference between i and some element after it so as to maximize x

profit.c

#include<stdio.h> 

int max(int a, int b) {
    return a > b ? a : b;
}

int max_profit(int* values, size_t len) {
    if (len == 1) return 0;

    int ret = 0;
    int cur = *values;
    int* upcoming = values + 1;

    for (int i = 0; i < len - 1; ++i) {
        int profit = *(upcoming + i) - cur;

        if (ret < profit) {
            ret = profit;
        }
    }

    return max(ret, max_profit(upcoming, len - 1));
}

int main() {
    int prices[6] = {10, 7, 5, 8, 11, 9};
    size_t len = 6;

    int profit = max_profit(prices, len);
    printf("You will earn $%d\n", profit);
    return 0;
}