java: add «122. Best Time to Buy and Sell Stock II»

URL:	https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/
Signed-off-by: Matej Focko <me@mfocko.xyz>

java/best-time-to-buy-and-sell-stock-ii.java

@@ -0,0 +1,13 @@
+class Solution {
+  public int maxProfit(int[] prices) {
+    var profit = 0;
+
+    for (var i = 1; i < prices.length; ++i) {
+      if (prices[i] > prices[i - 1]) {
+        profit += prices[i] - prices[i - 1];
+      }
+    }
+
+    return profit;
+  }
+}