4-15. The state diagram for a sequential circuit appears in Figure 4-51. (a) Find the state table for the circuit. (b) Make a state assignment for the circuit using 3-bit codes for the six states; make one of the code bits equal to the output to save logic, and find the encoded state table. The next states and outputs are don't cares for the two unused state codes. (e) Find an optimized circuit implementation using D flip-flops, NAND gates, and inverters. (d) Repeat parts (b) and (c) using one-hot encoding for the state assignment. Input X Output Z 0 A 0 B 0 Reset 1 1 0 0 1 C 0 D 1 1 0 0 0 E 1 F 1 1 O FIGURE 4-51 State Diagram for Problem 4-15