computeUpRightToDownFront method
int
computeUpRightToDownFront(
)
Implementation
int computeUpRightToDownFront() {
final edge = List.filled(6, Edge.upRight);
var a = 0, x = 0, b = 0;
// compute the index a < (12 choose 6) and the permutation array.
for (var j = Edge.upRight.index; j <= Edge.bottomRight.index; j++) {
if (_ep[j].index <= Edge.downFront.index) {
a += _cnk(j, x + 1);
edge[x++] = _ep[j];
}
}
// compute the index b < 6! for the permutation.
for (var j = 5; j > 0; j--) {
var k = 0;
while (edge[j].index != j) {
_rotateLeft(edge, 0, j);
k++;
}
b = (j + 1) * b + k;
}
return 720 * a + b;
}