a)

1.Qh4-f6! threat:

2.Qf6-d4 #

1...Kc5-c4

2.Qf6-c3 +

2...Kc4-d5

3.Qc3-d4 #

1...Kc5-b4

2.Qf6-c3 +

2...Kb4-a4

3.Qc3-a3 #

b) wRb6-->b4

1.Qh4-e7 + !

1...Kc5-d5

2.Qe7-d6 #

1...Kc5-c6

2.Qe7-c7 +

2...Kc6-d5

3.Qc7-d6 #

1...Kc5-b6

2.Qe7-c7 +

2...Kb6-a6

3.Qc7-a7 #

c) wSb5-->f6

1.Qh4-f2 + !

1...Kc5-c4

2.Qf2-d2 zugzwang.

2...Kc4-c5

3.Qd2-b4 #

d) wSb5-->f2

   1.Qh4-d8 ! zugzwang.

1...Kc5-c4

2.Qd8-d6 zugzwang.

2...Kc4-c3

3.Qd6-d3 #

solution finished. Time = 0.045 s