contains method
{@inheritDoc} */
Implementation
bool contains(int el) {
final n = intervals.length;
var l = 0;
var r = n - 1;
// Binary search for the element in the (sorted,
// disjoint) array of intervals.
while (l <= r) {
final m = ((l + r) / 2).floor();
final I = intervals[m];
final a = I.a;
final b = I.b;
if (b < el) {
l = m + 1;
} else if (a > el) {
r = m - 1;
} else {
// el >= a && el <= b
return true;
}
}
return false;
}