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c++dynamic-programmingsubset-sum

Below is the code for subset sum problem in gfg. Please tell me what is wrong in it


#include<iostream>
#include<bits/stdc++.h>
using namespace std;
#define ll long long
bool check(int a[], int n, int s)
{
    bool dp[n+1][s+1];
    for(int i=0;i<n+1;i++)
    {
        for(int j=0;j<s+1;j++)
        {
            if(i==0)
                dp[i][j] = false;
            if(j==0)
                dp[i][j] = true;
            if(a[i-1]<=j)
                dp[i][j] = dp[i-1][j-a[i-1]] || dp[i-1][j];
            else
                dp[i][j] = dp[i-1][j];
        }
    }
    return dp[n][s];
}
int main()
 {
    //code
    int t;
    cin>>t;
    while(t--)
    {
        int n;
        cin>>n;
        int arr[n];
        int s=0;
        for(int i=0;i<n;i++){
            cin>>arr[i];
            s+=arr[i];
        }
        if(s%2==0)
        {
            s/=2;
            if(check(arr,n,s))
                cout<<"YES\n";
            else
                cout<<"NO\n";
        }
        else
            cout<<"NO\n";
    }
    return 0;
}

The question is Given a set of numbers, check whether it can be partitioned into two subsets such that the sum of elements in both subsets is same or not.

For a test-case; 4 1 5 11 5 The output will be YES because There exists two subsets such that {1, 5, 5} and {11}.

The above test case is passed but it is showing wrong answer for 8 479 758 315 472 730 101 460 619 The actual answer should be YES but it is showing NO.


Solution

  • #include<iostream>
    #include<bits/stdc++.h>
    using namespace std;
    #define ll long long
    bool check(int a[], int n, int s)
    {
        bool dp[n+1][s+1];
        for(int i=0;i<n+1;i++)
        {
            for(int j=0;j<s+1;j++)
            {
                if(i==0)
                    dp[i][j] = false;
                else if(j==0)
                    dp[i][j] = true;
                else if(a[i-1]<=j)
                    dp[i][j] = dp[i-1][j-a[i-1]] || dp[i-1][j];
                else
                    dp[i][j] = dp[i-1][j];
            }
        }
        return dp[n][s];
    }
    int main()
     {
        //code
        int t;
        cin>>t;
        while(t--)
        {
            int n;
            cin>>n;
            int arr[n];
            int s=0;
            for(int i=0;i<n;i++){
                cin>>arr[i];
                s+=arr[i];
            }
            if(s%2==0)
            {
                s/=2;
                if(check(arr,n,s))
                    cout<<"YES\n";
                else
                    cout<<"NO\n";
            }
            else
                cout<<"NO\n";
        }
        return 0;
    }
    

    This is the corrected code.