slight update to 0121 solution

- skip repeated first index
- changed two if's to elif case for slight speed gains

Author: ab12gu

Diff for: python/0121-best-time-to-buy-and-sell-stock.py

@@ -1,10 +1,13 @@
 class Solution:
     def maxProfit(self, prices: List[int]) -> int:
-        res = 0
 
+        profit = 0
         lowest = prices[0]
-        for price in prices:
+        
+        for price in prices[1:]:
             if price < lowest:
                 lowest = price
-            res = max(res, price - lowest)
-        return res
+            elif price - lowest > profit:
+                profit = price - lowest
+
+        return profit