diff --git a/Best Time to Buy and Sell Stock IV.py b/Best Time to Buy and Sell Stock IV.py
new file mode 100644
index 0000000..ed23ad2
--- /dev/null
+++ b/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)
diff --git a/Best Time to Buy and Sell Stock-I.py b/Best Time to Buy and Sell Stock-I.py
new file mode 100644
index 0000000..c049900
--- /dev/null
+++ b/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)
diff --git a/Best Time to Buy and Sell Stock-II.py b/Best Time to Buy and Sell Stock-II.py
new file mode 100644
index 0000000..4252569
--- /dev/null
+++ b/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)
diff --git a/Best Time to Buy and Sell Stock-III.py b/Best Time to Buy and Sell Stock-III.py
new file mode 100644
index 0000000..7308f28
--- /dev/null
+++ b/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)