Best Time to Buy and Sell Stockeasy

fn max_profit(prices: Vec<i32>) -> i32 {
    // TODO: find the maximum profit from a single buy/sell
    0
}

fn main() {
    println!("{}", max_profit(vec![7, 1, 5, 3, 6, 4])); // 5
    println!("{}", max_profit(vec![7, 6, 4, 3, 1]));     // 0
}