CSE143 4-Queens Trace explore column 1 row 1 place explore column 2 row 1 row 2 row 3 place explore column 3 row 1 row 2 row 3 row 4 remove row 4 place explore column 3 row 1 row 2 place explore column 4 row 1 row 2 row 3 row 4 remove row 3 row 4 remove remove row 2 place explore column 2 row 1 row 2 row 3 row 4 place explore column 3 row 1 place explore column 4 row 1 row 2 row 3 place explore column 5 success! remove row 4 remove row 2 row 3 row 4 remove remove row 3 place explore column 2 row 1 place explore column 3 row 1 row 2 row 3 row 4 place explore column 4 row 1 row 2 place explore column 5 success! remove row 3 row 4 remove remove row 2 row 3 row 4 remove row 4 place explore column 2 row 1 place explore column 3 row 1 row 2 row 3 place explore column 4 row 1 row 2 row 3 row 4 remove row 4 remove row 2 place explore column 3 row 1 row 2 row 3 row 4 remove row 3 row 4 remove