This problem is quite obvious a dp problem
soup(n1, n2) = 0.25 * (soup(n1-100, n2) + soup(n1-75, n2-25)
+ soup(n1-50, n2-50) + soup(n1-25, n2-75))Note: soup(0, 0) = 0.5, soup(*, 0) = 0 and soup(0, *) = 1. when n1 and n2 is large enough, the probability is 1