I am trying the CSES problem set. I am getting WA on a few tests in Two Sets — II question. Here is the link for the code and the results https://cses.fi/problemset/result/911739/

My approach is to create a dp[i][j] which stores the number of ways to get sum i using first j indices. My target is to get sum n*(n-1)/4 . Formula I use is- dp[i][j]=dp[i][j-1]+dp[i-j][j-1];

I initialized dp[0][i] to 1 for all i<=n bcoz the only possible way is to select no indice at all. And also dp[i][0] to 0 for all 1<=i<=target bcoz its not possible to create a sum using no digits at all. I then print (dp[target][n])/2;

Please help. I am getting WA on few tests.