public List <int> Test(TreeNodeIb a)
{
var s = new Stack <TreeNodeIb>();
var r = new List <int>();
TreeNodeIb lastVisited = null;
while (s.Count != 0 || a != null)
{
if (a != null)
{
s.Push(a);
a = a.left;
}
else
{
// If the popped item has a right child and the right child is not
// processed yet, then make sure right child is processed before root
var p = s.Peek();
if (p.right != null && p.right != lastVisited)
{
a = p.right;
}
else
{
lastVisited = s.Pop();
r.Add(lastVisited.val);
}
}
}
return(r);
}
public void Flatten()
{
var root = new TreeNodeIb(3)
{
left = new TreeNodeIb(1), right = new TreeNodeIb(3)
};
if (root == null)
{
return;
}
var node = root;
while (node != null)
{
// Attatches the right sub-tree to the rightmost leaf of the left sub-tree:
if (node.left != null)
{
var rightMost = node.left;
while (rightMost.right != null)
{
rightMost = rightMost.right;
}
rightMost.right = node.right;
// Makes the left sub-tree to the right sub-tree:
node.right = node.left;
node.left = null;
}
// Flatten the rest of the tree:
node = node.right;
}
}
public void Flatten2()
{
var a = new TreeNodeIb(3)
{
left = new TreeNodeIb(1), right = new TreeNodeIb(5)
};
var s = new Stack <TreeNodeIb>();
var p = a;
while (p != null || s.Count > 0)
{
if (p.right != null)
{
s.Push(p.right);
}
if (p.left != null)
{
p.right = p.left;
p.left = null;
}
else
{
if (s.Count > 0)
{
var tmp = s.Pop();
p.right = tmp;
}
}
p = p.right;
}
}
private bool hasSum(TreeNodeIb root, int sum)
{
if (root == null)
{
return(sum == 0);
}
var subSum = sum - root.val;
if (subSum == 0 && root.left == null && root.right == null)
{
return(true);
}
var r = false;
if (root.left != null)
{
r = r || hasSum(root.left, subSum);
}
if (root.right != null)
{
r = r || hasSum(root.right, subSum);
}
return(r);
}
private void inorder(TreeNodeIb root)
{
if (root == null)
{
return;
}
inorder(root.left);
if (pre == null)
{
pre = root;
}
else
{
if (root.val < pre.val)
{
if (first == null)
{
first = pre;
}
second = root;
}
pre = root;
}
inorder(root.right);
}
private TreeNodeIb NonRecInvert(TreeNodeIb r)
{
var q = new Queue <TreeNodeIb>();
if (r != null)
{
q.Enqueue(r);
}
while (q.Count > 0)
{
var p = q.Dequeue();
if (p.left != null)
{
q.Enqueue(p.left);
}
if (p.right != null)
{
q.Enqueue(p.right);
}
var t = p.left;
p.left = p.right;
p.right = t;
}
return(r);
}
public int SumNumbers(TreeNodeIb root)
{
var result = 0;
if (root == null)
{
return(result);
}
var res = new List <List <TreeNodeIb> >();
var cur = new List <TreeNodeIb>();
cur.Add(root);
DFS(root, cur, res);
foreach (var nodes in res)
{
var sb = new StringBuilder();
foreach (var node in nodes)
{
sb.Append(node.val.ToString());
}
var currValue = int.Parse(sb.ToString());
result = result + currValue;
}
return(result);
}
public int T2Sum()
{
var root = new TreeNodeIb(10)
{
right = new TreeNodeIb(20), left = new TreeNodeIb(9)
};
var sum = 19;
var sumIb = new Bst(root);
var x1 = sumIb.Left();
var x2 = sumIb.Right();
while (x1 < x2)
{
if (x1 + x2 == sum)
{
return(1);
}
if (x1 + x2 < sum)
{
x1 = sumIb.Left();
}
else
{
x2 = sumIb.Right();
}
}
return(0);
}
public List <int> Test(TreeNodeIb a)
{
if (a == null)
{
return(null);
}
var s = new Stack <TreeNodeIb>();
var r = new List <int>();
s.Push(a);
while (s.Count > 0)
{
var p = s.Pop();
r.Add(p.val);
if (p.right != null)
{
s.Push(p.right);
}
if (p.left != null)
{
s.Push(p.left);
}
}
return(r);
}
public int IsBalanced()
{
var a = new TreeNodeIb(1);
var r = IsBalanced1(a);
return(r ? 1 : 0);
}
/// <summary>
/// max heap
/// </summary>
/// <param name="a"></param>
/// <param name="start"></param>
/// <param name="end"></param>
/// <returns></returns>
private TreeNodeIb build(List <int> a, int start, int end)
{
if (start > end)
{
return(null);
}
var minIndex = -1;
var min = int.MinValue;
for (var i = start;
i <= end;
i++)
{
if (a[i] > min)
{
minIndex = i;
min = a[i];
}
}
var n = new TreeNodeIb(a[minIndex]);
n.left = build(a, start, minIndex - 1);
n.right = build(a, minIndex + 1, end);
return(n);
}
private int GetHeight(TreeNodeIb root)
{
if (root == null)
{
return(-1);
}
return(1 + Math.Max(GetHeight(root.right), GetHeight(root.left)));
}
// efficient
public int lcaEff(TreeNodeIb a, int val1, int val2)
{
a = findLCA(a, val1, val2);
if (a == null)
{
return(-1);
}
return(a.val);
}
public List <List <int> > ZigzagLevelOrder(TreeNodeIb a)
{
if (a == null)
{
return(null);
}
var res = new List <List <int> >();
var q = new Queue <TreeNodeIb>();
q.Enqueue(a);
q.Enqueue(null); // sentinal
var dir = false; // dir = false => add on back if dir == true then add on front
var cur = new LinkedList <int>();
while (q.Count > 0)
{
var p = q.Dequeue();
if (p == null)
{
dir = !dir;
if (q.Count > 0)
{
q.Enqueue(null);
}
res.Add(new List <int>(cur));
cur.Clear();
continue;
}
if (p.left != null)
{
q.Enqueue(p.left);
}
if (p.right != null)
{
q.Enqueue(p.right);
}
if (dir)
{
cur.AddFirst(p.val);
}
else
{
cur.AddLast(p.val);
}
}
return(res);
}
private int getHeight(TreeNodeIb r)
{
if (r == null)
{
return(0);
}
return(1 + Math.Max(getHeight(r.left), getHeight(r.right)));
}
public int SumNumbers(TreeNodeIb a)
{
if (a == null)
{
return(0);
}
return(DFS(a, 0, 0) % 1003);
}
public int MaxDepth(TreeNodeIb a)
{
if (a == null)
{
return(0);
}
return(getHeight(a));
}
public int HasPathSum(TreeNodeIb root, int sum)
{
if (root == null)
{
return(0);
}
var r = hasSum(root, sum);
return(r ? 1 : 0);
}
public void LcaTest1()
{
var node = new TreeNodeIb(3);
node.left = new TreeNodeIb(5);
node.right = new TreeNodeIb(1);
var r = lca(node, 5, 1);
Assert.IsTrue(r == 3);
}
public void LcaTest2()
{
var node = new TreeNodeIb(3)
{
left = new TreeNodeIb(5),
right = new TreeNodeIb(1)
};
var r = lcaEff(node, 5, 1);
Assert.IsTrue(r == 3);
}
public List <int> RecoverTree(TreeNodeIb a)
{
inorder(a);
var list = new List <int>();
if (first != null && second != null)
{
list.Add(second.val);
list.Add(first.val);
}
return(list);
}
public void Main()
{
var root = new TreeNodeIb(2)
{
left = new TreeNodeIb(1)
};
var i = new BstIterator(root);
while (i.HasNext())
{
Console.WriteLine(i.HasNext());
}
}
private bool IsBalanced1(TreeNodeIb a)
{
if (a == null)
{
return(true);
}
var lh = GetHeight(a.left);
var rh = GetHeight(a.right);
var abs1 = Math.Abs(lh - rh);
var r = abs1 <= 1;
return(r && IsBalanced1(a.left) && IsBalanced1(a.right));
}
public List <List <int> > PathSum(TreeNodeIb root, int sum)
{
var r = new List <List <int> >();
if (root == null)
{
return(r);
}
var cur = new List <int>();
cur.Add(root.val);
ps(root, r, cur, sum - root.val);
return(r);
}
public TreeNodeIb Invert(TreeNodeIb r)
{
if (r == null)
{
return(null);
}
r.left = Invert(r.left);
r.right = Invert(r.right);
var t = r.left;
r.left = r.right;
r.right = t;
return(r);
}
private static int DFS(TreeNodeIb a, int num, int sum)
{
if (a == null)
{
return(sum % 1003);
}
num = (num * 10 + a.val) % 1003;
if (a.left == null && a.right == null)
{
sum = (sum + num) % 1003;
return(sum % 1003);
}
sum = (sum + DFS(a.left, num, sum) + DFS(a.right, num, sum)) % 1003;
return(sum % 1003);
}
private TreeNodeIb sortedArrayToBSTRec(List <int> a, int start, int finish)
{
if (start > finish)
{
return(null);
}
var m = start + (finish - start) / 2;
var left = sortedArrayToBSTRec(a, start, m - 1);
var root = new TreeNodeIb(a[m]);
var right = sortedArrayToBSTRec(a, m + 1, finish);
root.left = left;
root.right = right;
return(root);
}
private static TreeNodeIb Build(List <int> inOrder, List <int> postOrder, int inStart, int inEnd,
int postStart, int postEnd)
{
if (inStart > inEnd || postStart > postEnd)
{
return(null);
}
var node = new TreeNodeIb(postOrder[postEnd]);
var findIndex = Find(inOrder, inStart, inEnd, node.val);
node.left = Build(inOrder, postOrder, inStart, findIndex - 1,
postStart, postStart + findIndex - (inStart + 1));
node.right = Build(inOrder, postOrder, findIndex + 1, inEnd, postStart + findIndex - inStart,
postEnd - 1);
return(node);
}
private static bool FindPath(TreeNodeIb node, List <int> path, int k)
{
if (node == null)
{
return(false);
}
path.Add(node.val);
if (node.val == k)
{
return(true);
}
if (node.left != null && FindPath(node.left, path, k) ||
node.right != null && FindPath(node.right, path, k))
{
return(true);
}
path.RemoveAt(path.Count - 1);
return(false);
}
public int Kthsmallest(TreeNodeIb a, int b)
{
var s = new Stack <TreeNodeIb>();
// add sentinal
s.Push(null);
//move to left extremen (minimum)
var t = a;
while (t != null)
{
s.Push(t);
t = t.left;
}
TreeNodeIb res = null;
while (s.Count > 0)
{
res = s.Pop();
b--;
if (b == 0)
{
break;
}
if (res.right != null)
{
/* push the left subtree of right subtree */
var tmp = res.right;
while (tmp != null)
{
s.Push(tmp);
tmp = tmp.left;
}
}
}
return(res != null ? res.val : -1);
}