Based on the parity of the permutations defining the moves, check whether there are any parity constraints that make it impossible to have an even length solution and an odd length solution (e.g. 3x3x3 qtm). If there are any constraints, increment the depth by 2 at each stage of the search.
Based on the parity of the permutations defining the moves, check whether there are any parity constraints that make it impossible to have an even length solution and an odd length solution (e.g. 3x3x3 qtm). If there are any constraints, increment the depth by 2 at each stage of the search.