Merge pull request nirmalnishant645#11 from nirmalnishant645/problem

Best Time to Buy and Sell Stock

121-Best-Time-To-Buy-and-Sell-Stock.py

@@ -0,0 +1,31 @@
+'''
+Say you have an array for which the ith element is the price of a given stock on day i.
+
+If you were only permitted to complete at most one transaction (i.e., buy one and sell one share of the stock), design an algorithm to find the maximum profit.
+
+Note that you cannot sell a stock before you buy one.
+
+Example 1:
+
+Input: [7,1,5,3,6,4]
+Output: 5
+Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
+             Not 7-1 = 6, as selling price needs to be larger than buying price.
+Example 2:
+
+Input: [7,6,4,3,1]
+Output: 0
+Explanation: In this case, no transaction is done, i.e. max profit = 0.
+'''
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        if not prices:
+            return 0
+        profit,  mini = 0, prices[0]
+        for i in prices:
+            if i > mini:
+                if i - mini > profit:
+                    profit = i - mini
+            else:
+                mini = i
+        return profit