where is empty and { , ,cduring the executionall the permutations of the three characters are generated and tested note that the initial call makes three recursive callseach of which in turn makes two more if we had executed puzzlesolve( ,suon set consisting of four elementsthe initial call would have made four recursive callseach of which would have trace looking like the one in figure figure recursion trace for an execution of puzzlesolve( , , )where is empty and {abcthis execution generates and tests all permutations of aband we show the permutations generated directly below their respective boxes