Frog Jump


memo[ind][jumpsize] = ((ind == stones.length  1) ? 1 : 0);
Properly using parentheses makes expressions clear, but the outer parentheses in this statement look a bit overconservative.
http://introcs.cs.princeton.edu/java/11precedence/

This is not correct. You have an inner set. If there are n^2 states your inserting will be nnlg(nn) = nnlg(n) != nn. The analysis on why it's n*n "Two nested loops are there" is very weak. The first loops n times but how many times does the second loop? It's not n. It's at most n because otherwise you'd have reached the goal.
