A-6 Done

Best Time to Buy and Sell Stock IV.py

@@ -0,0 +1,28 @@
+class Solution:
+    def maxProfit(self, k: int, prices: List[int]) -> int:
+
+
+        if not prices:
+            return 0
+
+
+        if k>=len(prices)//2:
+            ans = 0
+            for i in range(1,len(prices)):
+                ans += max(0,prices[i]-prices[i-1])
+            return ans
+
+
+        cost = [float("inf") for i in range(k+1)]
+        profit = [0 for i in range((k+1))]
+
+        for price in prices:
+            for i in range(1,(k+1)):
+                cost[i] = min(cost[i], price-profit[i-1])
+                profit[i] = max(profit[i], price-cost[i])
+
+
+        return profit[-1]
+
+Time: NK
+Space: O(K)

Best Time to Buy and Sell Stock-I.py

@@ -0,0 +1,14 @@
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        profit = 0
+        lowSoFar = 1000000
+        for i in range(len(prices)):
+
+            lowSoFar = min(lowSoFar, prices[i])
+            profit = max(profit, prices[i]-lowSoFar)
+
+        return profit
+
+
+Time: O(N)
+Space: O(1)

Best Time to Buy and Sell Stock-II.py

@@ -0,0 +1,10 @@
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        sum = 0
+        for i in range(1,len(prices)):
+
+            sum += max(0, prices[i]-prices[i-1])
+
+        return sum
+Time: O(N)
+Space: O(1)

Best Time to Buy and Sell Stock-III.py

@@ -0,0 +1,22 @@
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        firstCost = float("inf")
+        secondCost = float("inf")
+
+        firstProfit = 0
+        secondProfit = 0
+
+
+        for cost in prices:
+
+            firstCost = min(firstCost, cost)
+
+            firstProfit = max(firstProfit, cost-firstCost)
+
+            secondCost = min(secondCost, cost-firstProfit)
+
+            secondProfit = max(secondProfit, cost-secondCost)
+
+        return secondProfit
+Time: O(N)
+Space: O(1)