For i = 0, you can calculate all valid j(ignoring k for now) in O(n^2). The number of valid j can be called val_j.
Note that if i = 1, each valid j is also incremented by one. Therefore, the total number of valid (i,j) pairs is n*val_j since i can be any value and there will always be the same number of valid j.
Next, we can repeat this logic with j and k. For a given j, the number of valid k is val_k and can be calculated in O(n^2).
The number of total valid j is the number of valid (i,j) pairs which were calculated above, so the answer is n*val_j*val_k.
For i = 0, you can calculate all valid j(ignoring k for now) in O(n^2). The number of valid j can be called
val_j.Note that if i = 1, each valid j is also incremented by one. Therefore, the total number of valid (i,j) pairs is
n*val_jsince i can be any value and there will always be the same number of valid j.Next, we can repeat this logic with j and k. For a given j, the number of valid k is
val_kand can be calculated in O(n^2).The number of total valid j is the number of valid (i,j) pairs which were calculated above, so the answer is
n*val_j*val_k.