0121买卖股票最佳时机添加 Java 版本实现

problems/0121.买卖股票的最佳时机.md

@@ -198,7 +198,22 @@ public:
 
 
 Java：
-
+```java
+class Solution {
+    public int maxProfit(int[] prices) {
+        int minprice = Integer.MAX_VALUE;
+        int maxprofit = 0;
+        for (int i = 0; i < prices.length; i++) {
+            if (prices[i] < minprice) {
+                minprice = prices[i];
+            } else if (prices[i] - minprice > maxprofit) {
+                maxprofit = prices[i] - minprice;
+            }
+        }
+        return maxprofit;
+    }
+}
+```
 
 Python：