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/*
* <!--
* This program is distributed under
* the terms of the MIT license.
* Please see the LICENSE file for details.
* -->
*/
/*
* Write a function that returns an array of all the factorials before a given
* number.
* For instance for 6 the function should return [720, 120, 24, 6, 2, 1]
*/
/*____________________________________________________________________________*/
/**
* @function {public static} getAllFactorials
*
* Gets all the factorials before n.
*
* @param {Integer} n - the number to get the factorials of.
*
* @return an `Array` containing all the factorials before n.
*/
function getAllFactorials(n) {
var stack = [];
factorial(n, stack, 0);
return stack;
}
/**
* Just for debugging.
*/
function trace(n, level) {
console.log('>>> n:' + n + ' level:' + level);
}
/**
* @function {public static} factorial
*
* Calculates the factorial and puts the result to a stack.
*
* @param {Integer} n - the number to calculate the factorial of.
* @param {Array} stack - call stack.
* @param {Integer} level - recursion depth.
*
* @return the factorial of the given number.
*/
function factorial(n, stack, level) {
if (n > 1) {
trace(n, level);
stack[level] = n * factorial(n-1, stack, level + 1);
return stack[level];
}
trace(n, level);
stack[level] = 1;
return stack[level];
}
/*____________________________________________________________________________*/
console.log(getAllFactorials(10));
/*
Output: ($ /usr/bin/node 002.js)
>>> n:10 level:0
>>> n:9 level:1
>>> n:8 level:2
>>> n:7 level:3
>>> n:6 level:4
>>> n:5 level:5
>>> n:4 level:6
>>> n:3 level:7
>>> n:2 level:8
>>> n:1 level:9
[ 3628800, 362880, 40320, 5040, 720, 120, 24, 6, 2, 1 ]
*/