Cartesian product of multiple arrays in JavaScript
algorithm, arrays, cartesian-product, javascript
Solution
Here is a functional solution to the problem (without any mutable variable!) using `reduce` and `flatten`, provided by `underscore.js`:
function cartesianProductOf() {
return _.reduce(arguments, function(a, b) {
return _.flatten(_.map(a, function(x) {
return _.map(b, function(y) {
return x.concat([y]);
});
}), true);
}, [ [] ]);
}
// [[1,3,"a"],[1,3,"b"],[1,4,"a"],[1,4,"b"],[2,3,"a"],[2,3,"b"],[2,4,"a"],[2,4,"b"]]
console.log(cartesianProductOf([1, 2], [3, 4], ['a']));
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore.js"></script>
Remark: This solution was inspired by http://cwestblog.com/2011/05/02/cartesian-product-of-multiple-arrays/
Problem
How would you implement the Cartesian product of multiple arrays in JavaScript? As an example, ``` cartesian([1, 2], [10, 20], [100, 200, 300]) ``` should return ``` [ [1, 10, 100], [1, 10, 200], [1, 10, 300], [2, 10, 100], [2, 10, 200] ... ] ```