Russain Doll

Author: Dipendra-Raghav

Dynamic Programming/Russian Doll.cpp

@@ -0,0 +1,53 @@
+class Solution {
+public:
+    int solvetab(vector<int> &nums)
+    {
+         vector<vector<int>> dp(nums.size()+3,vector<int>(nums.size()+3,0));
+        for(int curr= nums.size()-1;curr>=0;curr--)
+        {
+            for(int prev=curr-1;prev>=-1;prev--)
+            {
+                    
+                    int inc=0;
+                    //include
+                    if(prev==-1||nums[curr]>nums[prev])
+                    {
+                        inc= 1+dp[curr+1][curr+1];
+                    } 
+                    int excl=dp[curr+1][prev+1];
+                    dp[curr][prev+1]=max(inc,excl);
+
+            }
+        }
+        return dp[0][0];
+    }
+    int solve(vector<int> &nums,int i,int prev,vector<vector<int>> &dp)
+    {
+        //base condition
+        if(i>=nums.size())
+        {
+            return 0;
+        }
+        if(dp[i][prev+1]!=-1)
+        {
+            return dp[i][prev+1];
+        }
+        //exclude
+        int excl=solve(nums,i+1,prev,dp);
+        int inc=0;
+        //include
+        if(prev==-1||nums[i]>nums[prev])
+        {
+            inc= 1+solve(nums,i+1,i,dp);
+        }
+        
+        return dp[i][prev+1]=max(inc,excl);
+        
+    }
+    int lengthOfLIS(vector<int>& nums) {
+        // vector<vector<int>> dp(nums.size()+3,vector<int>(nums.size()+3,-1));
+        // return solve(nums,0,-1,dp);
+        return solvetab(nums);
+        
+    }
+};