Subset Sum with Recursion | memorization | DP

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Given a set of non-negative integers, and a value sum, determine if there is a subset of the given set with sum equal to given sum.

https://www.geeksforgeeks.org/subset-sum-problem-dp-25/


            Recursion                                     

     class Solution {

    

    static boolean isSumK(int[] nums, int curin, int curSum) {

        

        if(curSum==0) {

            return true;

        }

        

        if(curin<0) {

            return false;

        }

        

        return isSumK(nums, curin-1, curSum-nums[curin]) 

            || isSumK(nums, curin-1, curSum);

    }



With Memorization

class Solution{


    static int issum(int arr[], int indx, int sum, int dp[][]) {

        

        if(sum==0)

         return 1;

         

        if(indx<0)

         return 0;

        

        if(dp[indx][sum]!=-1)

         return dp[indx][sum];

         

        int pick = 0;

        if(sum>=arr[indx]) 

          pick = issum(arr, indx-1, sum-arr[indx],dp);

          

        int notpick = issum(arr, indx-1, sum,dp);

        

        if(pick==1 || notpick==1) 

         return dp[indx][sum] = 1;

         

        return dp[indx][sum] = 0;

    }

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