使用C ++查找值数组中的最大利润（max-min）

Question

I have a project that reads as follows:

Given an array of stock prices during the span of a single day in chronological order. Find the biggest profit that could have been made by first buying and then selling the stock. The function receives a pointer to an array, and a corresponding array size.

Basically I have to find a min value, and then find a max value (with a higher index) to yield the biggest possible profit. Max - Min.

Sample data:
price[0]=100; 
price[1]=5; 
price[2]=7; 
price[3]=34; 
price[4]=100;   
price[5]=2;     

Output Based on Sample Data: 
The best possible profit would be if one bought at point 1 and sold at point 4 for 100-5 = 95 a share.

I was thinking - I have two small min and max functions.
The Min function finds the min value returning the index of the min position.
Then we have the pointer move to the min_index +1 and pass that to the function to find the max value. Then the max function returns the max_index; Then we would take the max_index value and subtract the min_index value. I don't know if this is the best approach or even a good approach. I'm also not entirely sure of the best way to code this in c++
Thank you.

Answer 1

You may try:

int bestProfit(const std::vector<int>& v)
{
    if (v.empty()) {
        return 0;
    }
    int min = v[0];
    int profit = 0;
    for (auto e : v) {
        profit = std::max(profit, e - min);
        min = std::min(min, e);
    }
    return profit;
}

Answer 2

// Time zero: Buy and sell at the same time, no profit
int best_buy_index = 0;
int best_sell_index = 0;
int min_index = 0;
int best_profit = 0;

for (int i = 1; i < prices.size(); ++i) {
  // Profit we'd get if we had bought at the lowest price yet and sold now.
  int profit = (prices[i] - prices[min_index]);

  if (profit > best_profit) {
    // We found a better solution.
    best_buy_index = min_index;
    best_sell_index = i;
    best_profit = profit;
  } else if (prices[i] < prices[min_index]) {
    // Potentially better buy time.
    min_index = i;
  }
}