Create buy_sell_with_transaction_fee.cpp

Author: avidLearnerInProgress

Diff for: buy_sell_with_transaction_fee.cpp

@@ -0,0 +1,41 @@
+class Solution {
+public:
+    int dp[50001][2];
+    int solve(vector<int> &prices, int fee, int own, int index) {
+        
+        //basecase
+        if(index == prices.size()) 
+            return 0;
+        
+        if(dp[index][own] != -1) 
+            return dp[index][own];
+        
+        if(own) {
+            int case1 = prices[index] + solve(prices, fee, 0, index + 1);
+            int case2 = solve(prices, fee, 1, index + 1);
+            return dp[index][own] = max(case1, case2);
+        }
+        
+        else {   
+            int case1 = -(fee + prices[index]) + solve(prices, fee, 1, index + 1);
+            int case2 = solve(prices, fee, 0, index + 1);
+            return dp[index][own] = max(case1, case2);
+        }   
+    }
+    
+    int maxProfit(vector<int>& prices, int fee) {
+        
+        /*
+        n = len(prices)
+        if you own a stock at day `i`, you have two choices -
+            - sell the stock at day `i + 1` and find the max profit incurred after day `i + 1` to `n`
+            - do not sell the stock at day `i + 1` and find max profit incurred after day `i + 1` to `n`
+            
+        if you do not own a stock at day `i` you have two choices -
+            - own a stock at day `i + 1` and find the max profit incurred after day `i + 1` to `n`
+            - do not sell the stock at day `i + 1` and find max profit incurred after day `i + 1` to `n`
+        */
+        memset(dp, -1, sizeof dp);
+        return solve(prices, fee, 0, 0);
+    }
+};