4.6 Estimation 283 29. Recall Example 4.11. Write a pseudocode algorithm that prints out all allow- able colorings of the vertices a, b, c, and d as a four-symbol string using the symbols in C = {R, G, B, V). Use the two disjoint cases given in the solution to Example 4.11: when b and d are the same color, and when b and d are different colors