feat: add 0221 Best Time to Buy And Sell Stock solution

Author: hyogshin

best-time-to-buy-and-sell-stock/hyogshin.py

@@ -0,0 +1,8 @@
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        dp = [0] * (len(prices) + 1)
+        least_num = prices[0]
+        for i in range(len(prices)):
+            least_num = min(prices[i], least_num)
+            dp[i] = max(prices[i] - least_num, dp[i-1])
+        return max(dp)