public static BinaryTreeNodeWithParent <int> LCA(BinaryTreeNodeWithParent <int> node0,
BinaryTreeNodeWithParent <int> node1)
{
var hash = new HashSet <BinaryTreeNodeWithParent <int> >();
while (node0 != null || node1 != null)
{
// Ascend tree in tandem from these two nodes.
if (node0 != null)
{
if (!hash.Add(node0))
{
return(node0);
}
node0 = node0.Parent;
}
if (node1 != null)
{
if (!hash.Add(node1))
{
return(node1);
}
node1 = node1.Parent;
}
}
throw new ArgumentException("node0 and node1 are not in the same tree");
}
public void LCA()
{
var A = new BinaryTreeNodeWithParent <int>()
{
Data = 314
};
var B = new BinaryTreeNodeWithParent <int>()
{
Data = 6
};
var C = new BinaryTreeNodeWithParent <int>()
{
Data = 271
};
var D = new BinaryTreeNodeWithParent <int>()
{
Data = 28
};
var E = new BinaryTreeNodeWithParent <int>()
{
Data = 0
};
var F = new BinaryTreeNodeWithParent <int>()
{
Data = 561
};
var G = new BinaryTreeNodeWithParent <int>()
{
Data = 3
};
var H = new BinaryTreeNodeWithParent <int>()
{
Data = 17
};
var I = new BinaryTreeNodeWithParent <int>()
{
Data = 6
};
var J = new BinaryTreeNodeWithParent <int>()
{
Data = 2
};
var K = new BinaryTreeNodeWithParent <int>()
{
Data = 1
};
var L = new BinaryTreeNodeWithParent <int>()
{
Data = 401
};
var M = new BinaryTreeNodeWithParent <int>()
{
Data = 641
};
var N = new BinaryTreeNodeWithParent <int>()
{
Data = 257
};
var O = new BinaryTreeNodeWithParent <int>()
{
Data = 271
};
var P = new BinaryTreeNodeWithParent <int>()
{
Data = 28
};
B.Parent = A;
I.Parent = A;
C.Parent = B;
F.Parent = B;
D.Parent = C;
E.Parent = C;
G.Parent = F;
H.Parent = G;
J.Parent = I;
O.Parent = I;
K.Parent = J;
L.Parent = K;
N.Parent = K;
M.Parent = L;
P.Parent = O;
var result = Solution.LCA(M, N);
result.Data.Should().Be(K.Data);
}
