Stock prices I done

src/main/java/com/leetcode/arrays/BuySellStocks.java

@@ -0,0 +1,46 @@
+package com.leetcode.arrays;
+
+/**
+ * Problem: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
+ *
+ * @author rampatra
+ * @since 2019-04-23
+ */
+public class BuySellStocks {
+
+    /**
+     * Time complexity: O(n)
+     * where,
+     * n = no. of stock prices
+     * <p>
+     * Runtime: <a href="https://leetcode.com/submissions/detail/224463627/">0 ms</a>.
+     *
+     * @param prices
+     * @return
+     */
+    public static int maxProfit(int[] prices) {
+        int profit = 0;
+        int buyPrice = Integer.MAX_VALUE;
+
+        for (int i = 0; i < prices.length; i++) {
+            if (prices[i] < buyPrice) {
+                buyPrice = prices[i];
+            } else if (prices[i] - buyPrice > profit) {
+                profit = prices[i] - buyPrice;
+            }
+        }
+
+        return profit;
+    }
+
+    public static void main(String[] args) {
+
+        System.out.println(maxProfit(new int[]{7, 1, 5, 3, 6, 4}));
+        System.out.println(maxProfit(new int[]{7, 1, 5, 0, 6, 4}));
+        System.out.println(maxProfit(new int[]{4, 3, 2, 1}));
+
+        // edge cases
+        System.out.println(maxProfit(new int[]{}));
+        System.out.println(maxProfit(new int[]{1}));
+    }
+}