Check if one list contains all items from another list in order
This takes each part of ListA
and compares it with ListB
with SequenceEqual
:
bool containsSameSequence = ListA
.Where((item, index) => index <= ListA.Count - ListB.Count)
.Select((item, index) => ListA.Skip(index).Take(ListB.Count))
.Any(part => part.SequenceEqual(ListB));
Demo
It returns true
on the first matching sequence.
Here's a quick way:
var equal = listA.Count - listB.Count < 0
? false
: Enumerable.Range(0, listA.Count - listB.Count).Any(i =>
listA.Skip(i).Take(listB.Count).SequenceEqual(listB));
However, I'd prefer to use an extension method like this:
public static bool ContainsSequence<T>(this IEnumerable<T> outer,
IEnumerable<T> inner)
{
var innerCount = inner.Count();
for(int i = 0; i < outer.Count() - innerCount; i++)
{
if(outer.Skip(i).Take(innerCount).SequenceEqual(inner))
return true;
}
return false;
}
which you can call like:
var equals = listA.ContainsSequence(listB);
And here's a more efficient version of the same extension method specific to List<T>
:
public static bool ContainsSequence<T>(this List<T> outer, List<T> inner)
{
var innerCount = inner.Count;
for (int i = 0; i < outer.Count - innerCount; i++)
{
bool isMatch = true;
for (int x = 0; x < innerCount; x++)
{
if (!outer[i + x].Equals(inner[x]))
{
isMatch = false;
break;
}
}
if (isMatch) return true;
}
return false;
}