public void DoTest4()
{
var top = new AncestralTree('A');
var B = new AncestralTree('B');
var C = new AncestralTree('C');
top.AddAsAncestor(new AncestralTree[] { B, C });
var D = new AncestralTree('D');
var E = new AncestralTree('E');
B.AddAsAncestor(new AncestralTree[] { D, E });
var F = new AncestralTree('F');
var G = new AncestralTree('G');
C.AddAsAncestor(new AncestralTree[] { F, G });
var H = new AncestralTree('H');
var I = new AncestralTree('I');
D.AddAsAncestor(new AncestralTree[] { H, I });
Assert.That(GetYoungestCommonAncestor(top, H, G).name, Is.EqualTo('A'));
}
public static AncestralTree GetNthAncestor(AncestralTree person, int distance)
{
while (distance != 0)
{
person = person.ancestor;
--distance;
}
return(person);
}
public static int getDescendantDepth(AncestralTree descendant, AncestralTree topAncestor)
{
int depth = 0;
while (descendant != topAncestor)
{
depth++;
descendant = descendant.ancestor;
}
return(depth);
}
public static int GetDept(AncestralTree person)
{
int dept = 0;
while (person.ancestor != null)
{
person = person.ancestor;
++dept;
}
return(dept);
}
public static List <AncestralTree> GetLineage(AncestralTree person, List <AncestralTree> lineage)
{
if (person.ancestor == null)
{
lineage.Add(person);
return(lineage);
}
var theLineage = GetLineage(person.ancestor, lineage);
lineage.Add(person);
return(theLineage);
}
public static AncestralTree backtrackAncestralTree(AncestralTree lowerDescendant, AncestralTree higherDescendant, int diff)
{
while (diff > 0)
{
lowerDescendant = lowerDescendant.ancestor;
diff--;
}
while (lowerDescendant != higherDescendant)
{
lowerDescendant = lowerDescendant.ancestor;
higherDescendant = higherDescendant.ancestor;
}
return(lowerDescendant);
}
public static AncestralTree GetYoungestCommonAncestor(
AncestralTree topAncestor,
AncestralTree descendantOne,
AncestralTree descendantTwo
)
{
int depthOne = getDescendantDepth(descendantOne, topAncestor);
int depthTwo = getDescendantDepth(descendantTwo, topAncestor);
if (depthOne > depthTwo)
{
return(backtrackAncestralTree(descendantOne, descendantTwo, depthOne - depthTwo));
}
else
{
return(backtrackAncestralTree(descendantTwo, descendantOne, depthTwo - depthOne));
}
}
public static AncestralTree GetYoungestCommonAncestor(
AncestralTree topAncestor,
AncestralTree descendantOne,
AncestralTree descendantTwo
)
{
var lineageOne = GetLineage(descendantOne, new List <AncestralTree>());
var lineageTwo = GetLineage(descendantTwo, new List <AncestralTree>());
var lastCommon = topAncestor;
int i = 0;
while (i < Math.Min(lineageOne.Count, lineageTwo.Count) && lineageOne[i] == lineageTwo[i])
{
lastCommon = lineageOne[i];
++i;
}
return(lastCommon);
}
public static AncestralTree GetYoungestCommonAncestor(
AncestralTree topAncestor,
AncestralTree descendantOne,
AncestralTree descendantTwo
)
{
int deptOne = GetDept(descendantOne);
int deptTwo = GetDept(descendantTwo);
var yougest = deptOne > deptTwo ? descendantOne : descendantTwo;
var oldest = deptOne > deptTwo ? descendantTwo : descendantOne;
int distanceFromYoungest = Math.Max(deptOne, deptTwo) - Math.Min(deptOne, deptTwo);
var sameLevelAncestor = GetNthAncestor(yougest, distanceFromYoungest);
while (oldest.name != sameLevelAncestor.name)
{
oldest = oldest.ancestor;
sameLevelAncestor = sameLevelAncestor.ancestor;
}
return(oldest);
}
public AncestralTree(char name)
{
this.name = name;
this.ancestor = null;
}
