v0.40: Create exercises. Challenge the community.

hanoi-moves

Your mission

Write a program that prints the moves solving the Tower of Hanoi for the disk count given as its single argument, one move per line.

See it in action

./hanoi_moves 1 | cat -e

Expected result

A C$

Your checklist

For your own tracking. Tests grade your code.

Read the disk count from argv[1] and parse it with atoi.
The towers are named A, B and C. Every disk starts on A, all of them must end on C, and B is the spare tower.
A move is one line: the source tower, a single space, the destination tower, then a newline. Taking the top disk of A and dropping it on C prints A C.
Recurse in the canonical order, which makes the sequence unique. To move count disks from X to Z through Y: move count - 1 disks from X to Y, print the move X Z, then move count - 1 disks from Y to Z.
A count of n takes 2^n - 1 moves, so 3 disks print 7 lines and 6 disks print 63. What is graded is the lines, in order, not their total.
A count of zero prints nothing at all.
A negative count prints nothing either, and an argument that is not a number reads as zero, so it prints nothing too.
If the program does not receive exactly one argument (argc must be 2), print wrong number of arguments followed by a newline.

More examples

./hanoi_moves 2 | cat -e

Expected result

A B$
A C$
B C$

./hanoi_moves 3 | cat -e

Expected result

A C$
A B$
C B$
A C$
B A$
B C$
A C$

./hanoi_moves 0 | cat -e

Expected result

(empty result)

./hanoi_moves 3 2 | cat -e

Expected result

wrong number of arguments$

Constraints

Expected files

hanoi_moves.c

Allowed functions

atoiwrite

hanoi-moves

Recursion

Your mission

Write a program that prints the moves solving the Tower of Hanoi for the disk count given as its single argument, one move per line.

See it in action

./hanoi_moves 1 | cat -e

Expected result

A C$

Your checklist

For your own tracking. Tests grade your code.

Read the disk count from argv[1] and parse it with atoi.
The towers are named A, B and C. Every disk starts on A, all of them must end on C, and B is the spare tower.
A move is one line: the source tower, a single space, the destination tower, then a newline. Taking the top disk of A and dropping it on C prints A C.
Recurse in the canonical order, which makes the sequence unique. To move count disks from X to Z through Y: move count - 1 disks from X to Y, print the move X Z, then move count - 1 disks from Y to Z.
A count of n takes 2^n - 1 moves, so 3 disks print 7 lines and 6 disks print 63. What is graded is the lines, in order, not their total.
A count of zero prints nothing at all.
A negative count prints nothing either, and an argument that is not a number reads as zero, so it prints nothing too.
If the program does not receive exactly one argument (argc must be 2), print wrong number of arguments followed by a newline.

More examples

./hanoi_moves 2 | cat -e

Expected result

A B$
A C$
B C$

./hanoi_moves 3 | cat -e

Expected result

A C$
A B$
C B$
A C$
B A$
B C$
A C$

./hanoi_moves 0 | cat -e

Expected result

(empty result)

./hanoi_moves 3 2 | cat -e

Expected result

wrong number of arguments$

Constraints

Expected files

hanoi_moves.c

Allowed functions

atoiwrite

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01No argumentsWaiting

02Two argumentsWaiting

03Zero disks prints nothingWaiting

04One disk is a single moveWaiting

05Two disksWaiting

06Three disksWaiting

07Four disksWaiting

08Five disksWaiting

09Six disks is sixty-three movesWaiting

10Negative count prints nothingWaiting

11Non-numeric count prints nothingWaiting

12Empty argument prints nothingWaiting

hanoi-moves

Your mission

Write a program that prints the moves solving the Tower of Hanoi for the disk count given as its single argument, one move per line.

See it in action

./hanoi_moves 1 | cat -e

Expected result

A C$

Your checklist

For your own tracking. Tests grade your code.

Read the disk count from argv[1] and parse it with atoi.
The towers are named A, B and C. Every disk starts on A, all of them must end on C, and B is the spare tower.
A move is one line: the source tower, a single space, the destination tower, then a newline. Taking the top disk of A and dropping it on C prints A C.
Recurse in the canonical order, which makes the sequence unique. To move count disks from X to Z through Y: move count - 1 disks from X to Y, print the move X Z, then move count - 1 disks from Y to Z.
A count of n takes 2^n - 1 moves, so 3 disks print 7 lines and 6 disks print 63. What is graded is the lines, in order, not their total.
A count of zero prints nothing at all.
A negative count prints nothing either, and an argument that is not a number reads as zero, so it prints nothing too.
If the program does not receive exactly one argument (argc must be 2), print wrong number of arguments followed by a newline.

More examples

./hanoi_moves 2 | cat -e

Expected result

A B$
A C$
B C$

./hanoi_moves 3 | cat -e

Expected result

A C$
A B$
C B$
A C$
B A$
B C$
A C$

./hanoi_moves 0 | cat -e

Expected result

(empty result)

./hanoi_moves 3 2 | cat -e

Expected result

wrong number of arguments$

Constraints

Expected files

hanoi_moves.c

Allowed functions

atoiwrite

v0.40: Create exercises. Challenge the community.

Meet Studio →

hanoi-moves

Recursion

Your mission

Write a program that prints the moves solving the Tower of Hanoi for the disk count given as its single argument, one move per line.

See it in action

./hanoi_moves 1 | cat -e

Expected result

A C$

Your checklist

For your own tracking. Tests grade your code.

Read the disk count from argv[1] and parse it with atoi.
The towers are named A, B and C. Every disk starts on A, all of them must end on C, and B is the spare tower.
A move is one line: the source tower, a single space, the destination tower, then a newline. Taking the top disk of A and dropping it on C prints A C.
Recurse in the canonical order, which makes the sequence unique. To move count disks from X to Z through Y: move count - 1 disks from X to Y, print the move X Z, then move count - 1 disks from Y to Z.
A count of n takes 2^n - 1 moves, so 3 disks print 7 lines and 6 disks print 63. What is graded is the lines, in order, not their total.
A count of zero prints nothing at all.
A negative count prints nothing either, and an argument that is not a number reads as zero, so it prints nothing too.
If the program does not receive exactly one argument (argc must be 2), print wrong number of arguments followed by a newline.

More examples

./hanoi_moves 2 | cat -e

Expected result

A B$
A C$
B C$

./hanoi_moves 3 | cat -e

Expected result

A C$
A B$
C B$
A C$
B A$
B C$
A C$

./hanoi_moves 0 | cat -e

Expected result

(empty result)

./hanoi_moves 3 2 | cat -e

Expected result

wrong number of arguments$

Constraints

Expected files

hanoi_moves.c

Allowed functions

atoiwrite

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01No argumentsWaiting

02Two argumentsWaiting

03Zero disks prints nothingWaiting

04One disk is a single moveWaiting

05Two disksWaiting

06Three disksWaiting

07Four disksWaiting

08Five disksWaiting

09Six disks is sixty-three movesWaiting

10Negative count prints nothingWaiting

11Non-numeric count prints nothingWaiting

12Empty argument prints nothingWaiting