new DP problem added

Author: dev7omprakash

20. Dynamic Programming/BestTimeToBuyAndSellStockThree.java

@@ -0,0 +1,43 @@
+//Question Link= https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/
+
+
+import java.util.*;
+
+public class BestTimeToBuyAndSellStockThree{
+
+    public static void main(String[] args) throws Exception { 
+      int prices[]={1,3,4,2,6,1,6};
+      System.out.println(maxProfit(prices));
+    }
+
+
+    public static int maxProfit(int[] prices) {
+          Map<String,Integer> mp=new HashMap<>();
+          return solve(prices,0,true,2,mp);
+    }
+
+    public static int solve(int price[],int i,boolean canBuy,int count,Map<String,Integer> mp){
+
+        if(i>=price.length || count<=0) return 0;
+
+          String key=i+"!"+canBuy+"!"+count;
+
+        if(mp.containsKey(key)) return mp.get(key);
+
+        if(canBuy){
+
+           int idle=solve(price,i+1,canBuy,count,mp);
+           int buying=(-1*price[i])+solve(price,i+1,false,count,mp);
+           mp.put(key,Math.max(idle,buying));
+           return mp.get(key);
+
+        }else{
+
+           int idle=solve(price,i+1,canBuy,count,mp);
+           int selling=price[i]+solve(price,i+1,true,count-1,mp);
+           mp.put(key,Math.max(idle,selling)); 
+           return mp.get(key);
+
+        }
+    }
+  }