some more problems

best-time-to-buy-and-sell-stock/sol.rs

@@ -0,0 +1,12 @@
+impl Solution {
+    pub fn max_profit(prices: Vec<i32>) -> i32 {
+        prices
+            .iter()
+            .fold((prices[0], 0), |(min, max_diff), &price| {
+                if price < min {
+                    return (price, max_diff);
+                }
+                (min, max_diff.max(price - min))
+            }).1
+    }
+}