feat(array): Buy sell stocks

README.md

@@ -4,4 +4,8 @@
 
 ### 1. Two Sum
 
-> Use HashMap to determine indexes
+> Use HashMap to determine indexes - O(n)
+
+### 2. Buy Sell Stocks
+
+> Keep finding minimum and updating maxProfit for each iteration - O(n)

array/buy-sell-stocks.js

@@ -0,0 +1,15 @@
+/**
+ * @param {number[]} prices
+ * @return {number}
+ */
+var maxProfit = function(prices) {
+    let min = Number.MAX_SAFE_INTEGER
+    let maxProfit = 0;
+    for(let i = 0; i < prices.length; i++) {
+        const curr = prices[i];
+        const profit = curr - min;
+        min = Math.min(curr, min)
+        maxProfit = Math.max(profit, maxProfit)
+    } 
+    return maxProfit;
+};