https://codility.com/demo/take-sample-test/passing_cars/

Codility-3-1

function solution(A) {

    var cars0 = 0,
        cars1 = 0,
        combinations = 0;
        
    for (var i = A.length - 1; i >= 0; i--) {

        if (A[i] === 0) {
        
            cars0++;
            combinations += cars1;
        }
        else {
            
            cars1++;
        }
        console.log("Combinations for A[" + i + "]:" + combinations);
        if (combinations > 1000000000) return -1;
    }
    
    return combinations;
}