public void TestOrder()
{
var first = new Interval(7, 1);
var second = new Interval(5, 3);
var sorted = Intervals.Order(new Interval[] { second, first });
Assert.AreEqual(2, sorted.Count);
Assert.ReferenceEquals(first, sorted[0]);
Assert.ReferenceEquals(second, sorted[1]);
}
public void TestMerge()
{
var first = new Interval(5, 1);
var second = new Interval(9, 3);
var third = new Interval(12, 7);
var merged = Intervals.Merge(new Interval[] { second, third, first });
Assert.AreEqual(1, merged.Count);
Assert.AreEqual(first.a, merged[0].a);
Assert.AreEqual(third.b, merged[0].b);
}
/// <summary>
/// If intervals intersect, returns a new merged interval. Otherwise, returns null.
/// </summary>
/// <param name="i1"></param>
/// <param name="i2"></param>
/// <returns></returns>
public static Interval MergeTwo(Interval i1, Interval i2)
{
// order intervals
var first = i1.a <= i2.a ? i1 : i2;
var next = (first == i1) ? i2 : i1;
// do intervals intersect?
if(next.a >= first.a && next.a <= first.b)
return new Interval(first.a, Math.Max(first.b, next.b));
return null;
}
public static List<Interval> Merge(IEnumerable<Interval> intervals)
{
var result = new List<Interval>();
Interval prev = null;
foreach(var curr in Order(intervals)) {
if(prev == null) {
prev = new Interval(curr);
continue;
}
var merged = MergeTwo(prev, curr);
if(merged == null) {
result.Add(prev);
prev = curr;
}
else
prev = merged;
}
if(prev != null)
result.Add(prev);
return result;
}
public Interval(Interval clone)
{
a = clone.a;
b = clone.b;
}