Best Time to Buy and Sell Stock Problem & Solution

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 the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

See the best time to buy and sell stock problem on LeetCode.

C++ Solution

#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")

static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

class Solution {
  int maxProfit(vector<int>& prices) {
    int min_value = INT_MAX;
    int result = 0;

    for (int i = 0; i < prices.size(); ++i) {
      if (min_value > prices[i]) {
        min_value = prices[i];
      } else if (prices[i] - min_value > result) {
        result = prices[i] - min_value;

    return result;

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