For this problem, check how many comparisons you need to do.
L1: Number of 0 in the beginning should be equal to sum of the number of 1 & 0 thereafter. Only one comparison needed which can be solved using single stack. So, CFL.
L2: Number of 0 in the beginning should be equal to number of 1 thereafter & number of 0 should be less than both of them. Two comparisons needed which can be solved using two stacks. So, CSL.
L3: Number of 0 in the beginning should be equal to number of 1 & number of 0 thereafter. Two comparisons needed which can be solved using two stacks. So, CSL.
