In an alternating permutation of numbers 1 to n, the numbers are arranged so that they alternately increase and decrease. For example, there are five alternating permutations of the numbers 1, 2, 3, and 4:
1 3 2 4
1 4 2 3
2 3 1 4
2 4 1 3
3 4 1 2
Write a function to count the alternating permutations for a set of n numbers.
Solution Stats
Problem Comments
3 Comments
Solution Comments
Show comments
Loading...
Problem Recent Solvers10
Suggested Problems
-
Number of 1s in the Binary Representation of a Number
482 Solvers
-
Back to basics 9 - Indexed References
463 Solvers
-
1237 Solvers
-
There are 10 types of people in the world
1371 Solvers
-
Divide the Least Common Multiple by the Greatest Common Divisor of two numbers
53 Solvers
More from this Author323
Problem Tags
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
The test case result for n=5 seems a tad high.
Tim, that last case is altperm(altperm(5)). I did that to discourage lookup solutions.
Oops--my mistake.