4. Another generator for the n-Queens Problem is: Place a Queen in row 1.

Do not place the second Queen in any square that is attacked by the first Queen. In state i, place a Queen in column i in a square that is not under attack from any of the previous i-1 Queens. See Figure 2.34.

a. Solve the 4-Queens problem using this generator.

b. Argue that this generator is more informed than either of the two generators used in the text.

c. Draw the portion of the search tree expanded in the search for a first solution.