Add best-time-to-buy-and-sell-stock solution in TypeScript

Author: Jeehay28

best-time-to-buy-and-sell-stock/Jeehay28.ts

@@ -0,0 +1,21 @@
+// Time Complexity: O(n), where n is the length of the prices array
+// Space Complexity: O(1)
+
+function maxProfit(prices: number[]): number {
+  // input: an array prices, prices[i] = the stock price of ith day
+  // output: the maximum profit || 0
+
+  // prices = [7, 1, 5, 3, 6, 4]
+  // buy = 1, sell = 6, profit = 6 -1 = 5
+
+  let minBuy = prices[0];
+  let maxProfit = 0;
+
+  for (let i = 1; i < prices.length; i++) {
+    minBuy = Math.min(prices[i], minBuy);
+    maxProfit = Math.max(prices[i] - minBuy, maxProfit);
+  }
+
+  return maxProfit;
+}
+