1.3 KiB
| id | title | challengeType | forumTopicId | dashedName |
|---|---|---|---|---|
| 594810f028c0303b75339acf | Ackermann function | 5 | 302223 | ackermann-function |
--description--
The Ackermann function is a classic example of a recursive function, notable especially because it is not a primitive recursive function. It grows very quickly in value, as does the size of its call tree.
The Ackermann function is usually defined as follows:
A(m, n) = \\begin{cases} n+1 & \\mbox{if } m = 0 \\\\ A(m-1, 1) & \\mbox{if } m > 0 \\mbox{ and } n = 0 \\\\ A(m-1, A(m, n-1)) & \\mbox{if } m > 0 \\mbox{ and } n > 0. \\end{cases}
Its arguments are never negative and it always terminates.
--instructions--
Write a function which returns the value of A(m, n). Arbitrary precision is preferred (since the function grows so quickly), but not required.
--hints--
ack should be a function.
assert(typeof ack === 'function');
ack(0, 0) should return 1.
assert(ack(0, 0) === 1);
ack(1, 1) should return 3.
assert(ack(1, 1) === 3);
ack(2, 5) should return 13.
assert(ack(2, 5) === 13);
ack(3, 3) should return 61.
assert(ack(3, 3) === 61);
--seed--
--seed-contents--
function ack(m, n) {
}
--solutions--
function ack(m, n) {
return m === 0 ? n + 1 : ack(m - 1, n === 0 ? 1 : ack(m, n - 1));
}