Finding All Combinations (Cartesian product) of JavaScript array values
algorithm, javascript
Solution
This is not permutations, see permutations definitions from Wikipedia.
But you can achieve this with recursion:
var allArrays = [
['a', 'b'],
['c'],
['d', 'e', 'f']
]
function allPossibleCases(arr) {
if (arr.length == 1) {
return arr[0];
} else {
var result = [];
var allCasesOfRest = allPossibleCases(arr.slice(1)); // recur with the rest of array
for (var i = 0; i < allCasesOfRest.length; i++) {
for (var j = 0; j < arr[0].length; j++) {
result.push(arr[0][j] + allCasesOfRest[i]);
}
}
return result;
}
}
console.log(allPossibleCases(allArrays))
You can also make it with loops, but it will be a bit tricky and will require implementing your own analogue of stack.
Problem
How can I produce all of the combinations of the values in N number of JavaScript arrays of variable lengths? Let's say I have N number of JavaScript arrays, e.g. ``` var first = ['a', 'b', 'c', 'd']; var second = ['e']; var third = ['f', 'g', 'h', 'i', 'j']; ``` (Three arrays in this example, but its N number of arrays for the problem.) And I want to output all the combinations of their values, to produce ``` aef aeg aeh aei aej bef beg .... dej ``` EDIT: Here's the version I got working, using ffriend's accepted answer as the basis. ``` var allArrays = [['a', 'b'], ['c', 'z'], ['d', 'e', 'f']]; function allPossibleCases(arr) { if (arr.length === 0) { return []; } else if (arr.length ===1){ return arr[0]; } else { var result = []; var allCasesOfRest = allPossibleCases(arr.slice(1)); // recur with the rest of array for (var c in allCasesOfRest) { for (var i = 0; i < arr[0].length; i++) { result.push(arr[0][i] + allCasesOfRest[c]); } } return result; } } var results = allPossibleCases(allArrays); //outputs ["acd", "bcd", "azd", "bzd", "ace", "bce", "aze", "bze", "acf", "bcf", "azf", "bzf"] ```