public static void ConstructRightSibling(BinaryTreeNodeWithNext <int> tree)
{
var leftStart = tree;
while (leftStart != null && leftStart.Left != null)
{
PopulateLowerLevelNextField(leftStart);
leftStart = leftStart.Left;
}
}
private static void PopulateLowerLevelNextField(BinaryTreeNodeWithNext <int> startNode)
{
var iter = startNode;
while (iter != null)
{
// Populate left child’s next field.
iter.Left.Next = iter.Right;
// Populate right child’s next field if iter is not the last node of this
// level.
if (iter.Next != null)
{
iter.Right.Next = iter.Next.Left;
}
iter = iter.Next;
}
}
public void ConstructRightSibling()
{
var A = new BinaryTreeNodeWithNext <int> {
Data = 1
};
var B = new BinaryTreeNodeWithNext <int> {
Data = 2
};
var C = new BinaryTreeNodeWithNext <int> {
Data = 3
};
var D = new BinaryTreeNodeWithNext <int> {
Data = 4
};
var E = new BinaryTreeNodeWithNext <int> {
Data = 5
};
var F = new BinaryTreeNodeWithNext <int> {
Data = 6
};
var G = new BinaryTreeNodeWithNext <int> {
Data = 7
};
var H = new BinaryTreeNodeWithNext <int> {
Data = 8
};
var I = new BinaryTreeNodeWithNext <int> {
Data = 9
};
var J = new BinaryTreeNodeWithNext <int> {
Data = 10
};
var K = new BinaryTreeNodeWithNext <int> {
Data = 11
};
var L = new BinaryTreeNodeWithNext <int> {
Data = 12
};
var M = new BinaryTreeNodeWithNext <int> {
Data = 13
};
var N = new BinaryTreeNodeWithNext <int> {
Data = 14
};
var O = new BinaryTreeNodeWithNext <int> {
Data = 15
};
A.Left = B;
B.Left = C;
C.Left = D;
C.Right = E;
B.Right = F;
F.Left = G;
F.Right = H;
A.Right = I;
I.Left = J;
J.Left = K;
J.Right = L;
I.Right = M;
M.Left = N;
M.Right = O;
Solution.ConstructRightSibling(A);
A.Next.Should().BeNull();
B.Next.Should().BeEquivalentTo(I);
C.Next.Should().BeEquivalentTo(F);
D.Next.Should().BeEquivalentTo(E);
E.Next.Should().BeEquivalentTo(G);
F.Next.Should().BeEquivalentTo(J);
G.Next.Should().BeEquivalentTo(H);
H.Next.Should().BeEquivalentTo(K);
I.Next.Should().BeNull();
J.Next.Should().BeEquivalentTo(M);
K.Next.Should().BeEquivalentTo(L);
L.Next.Should().BeEquivalentTo(N);
M.Next.Should().BeNull();
N.Next.Should().BeEquivalentTo(O);
O.Next.Should().BeNull();
}
