public int KthSmallest(TreeNode root, int k)
{
Dictionary<TreeNode, int> map = new Dictionary<TreeNode, int>();
Recur(root, map);
var curnode = root;
while(true)
{
if (curnode.left != null)
{
if (k > map[curnode.left])
{
k -= map[curnode.left];
if (k == 1)
return curnode.val;
k--;
curnode = curnode.right;
}
else
{
curnode = curnode.left;
}
}
else
{
if (k == 1)
return curnode.val;
k--;
curnode = curnode.right;
}
}
}
public int KthSmallest3(TreeNode root, int k)
{
Stack<TreeNode> st = new Stack<TreeNode>();
var tmp = root;
while(tmp != null)
{
st.Push(tmp);
tmp = tmp.left;
}
while(st.Count() > 0)
{
var cur = st.Pop();
k--;
if (k == 0)
return cur.val;
if (cur.right != null)
{
tmp = cur.right;
while(tmp != null)
{
st.Push(tmp);
tmp = tmp.left;
}
}
}
return 0;
}
bool checkBST(TreeNode node, Stack<int> lst, Stack<int> rst)
{
bool re = true;
if (lst.Count != 0)
{
int lval = lst.Peek();
if (node.val > lval)
return false;
}
if (rst.Count != 0)
{
int rval = rst.Peek();
if (node.val < rval)
return false;
}
if (node.left != null)
{
lst.Push(node.val);
if(!checkBST(node.left, lst, rst))
return false;
lst.Pop();
}
if (node.right != null)
{
rst.Push(node.val);
if (!checkBST(node.right, lst, rst))
return false;
rst.Pop();
}
return re;
}
public TreeNode SortedListToBST(ListNode head)
{
if (head == null)
return null;
if (head.next == null)
return new TreeNode(head.val);
ListNode p = head;
ListNode q = head;
ListNode pre = q;
while(p != null && p.next != null)
{
pre = q;
q = q.next;
p = p.next.next;
}
TreeNode tn = new TreeNode(q.val);
if (q == head)
{
tn.right = new TreeNode(q.next.val);
}
else
{
tn = new TreeNode(q.val);
pre.next = null;
tn.left = SortedListToBST(head);
tn.right = SortedListToBST(q.next);
}
return tn;
}
public int SumNumbers(TreeNode root)
{
Stack<TreeNode> st = new Stack<TreeNode>();
Stack<int> vst = new Stack<int>();
if (root == null)
return 0;
int re = 0;
st.Push(root);
vst.Push(0);
while (st.Count != 0)
{
TreeNode cur = st.Pop();
int cval = vst.Pop();
if (cur.left == null && cur.right == null)
re += cval + cur.val;
if (cur.left != null)
{
st.Push(cur.left);
vst.Push((cval + cur.val) * 10);
}
if (cur.right != null)
{
st.Push(cur.right);
vst.Push((cval + cur.val) * 10);
}
}
return re;
}
public IList<int> InorderTraversal(TreeNode root)
{
var re = new List<int>();
Recur(root, re);
return re;
}
public static void Run()
{
var st = new Solution98();
Console.WriteLine("Start: {0}", DateTime.Now);
TreeNode tn = new TreeNode(3);
TreeNode tn1 = new TreeNode(1);
TreeNode tn2 = new TreeNode(8);
TreeNode tn3 = new TreeNode(4);
TreeNode tn4 = new TreeNode(5);
TreeNode tn5 = new TreeNode(6);
TreeNode tn6 = new TreeNode(7);
tn.left = tn1;
tn.right = tn3;
tn1.left = null;
tn1.right = tn2;
tn3.left = null;
tn3.right = tn4;
tn4.left = null;
tn4.right = tn5;
tn5.left = null;
tn5.right = tn6;
var re = st.IsValidBST(tn);
Console.WriteLine(re);
Console.WriteLine("End: {0}", DateTime.Now);
}
public bool HasPathSum(TreeNode root, int sum)
{
Queue<Tuple<TreeNode, int>> q = new Queue<Tuple<TreeNode, int>>();
if (root == null)
return false;
q.Enqueue(new Tuple<TreeNode, int>(root, root.val));
while(q.Count > 0)
{
var item = q.Dequeue();
var node = item.Item1;
var ts = item.Item2;
if (node.left == null && node.right == null && ts == sum)
return true;
if (node.left != null)
q.Enqueue(new Tuple<TreeNode, int>(node.left, ts + node.left.val));
if (node.right != null)
q.Enqueue(new Tuple<TreeNode, int>(node.right, ts + node.right.val));
}
return false;
}
public static void Run()
{
var st = new Solution103();
Console.WriteLine("Start: {0}", DateTime.Now);
TreeNode tn = new TreeNode(3);
tn.left = new TreeNode(9);
tn.right = new TreeNode(20);
tn.right.left = new TreeNode(15);
tn.right.right = new TreeNode(7);
var re = st.ZigzagLevelOrder(tn);
foreach (var lt in re)
{
foreach (var data in lt)
Console.Write("{0} ", data);
Console.WriteLine();
}
Console.WriteLine("End: {0}", DateTime.Now);
}
public IList<int> PreorderTraversal(TreeNode root)
{
var re = new List<int>();
if (root == null)
return re;
var st = new Stack<TreeNode>();
st.Push(root);
re.Add(root.val);
while (root.left != null)
{
root = root.left;
st.Push(root);
re.Add(root.val);
}
while (st.Count() > 0)
{
var node = st.Pop();
var right = node.right;
while (right != null)
{
st.Push(right);
re.Add(right.val);
right = right.left;
}
}
return re;
}
public IList<IList<int>> PathSum(TreeNode root, int sum)
{
List<IList<int>> list = new List<IList<int>>();
if (root == null)
return list;
Queue<Tuple<TreeNode, int, List<int>>> st = new Queue<Tuple<TreeNode, int, List<int>>>();
st.Enqueue(new Tuple<TreeNode, int, List<int>> ( root, sum, new List<int>() ));
while(st.Count > 0)
{
var item = st.Dequeue();
var tn = item.Item1;
var sn = item.Item2;
var cl = item.Item3;
cl.Add(tn.val);
if (tn.left == null && tn.right == null && tn.val == sn)
{
list.Add(cl);
}
if (tn.left != null)
{
st.Enqueue(new Tuple<TreeNode, int, List<int>>(tn.left, sn - tn.val, cl));
if (tn.right != null)
st.Enqueue(new Tuple<TreeNode, int, List<int>>(tn.right, sn - tn.val, new List<int>(cl)));
}
else if (tn.right != null)
{
st.Enqueue(new Tuple<TreeNode, int, List<int>>(tn.right, sn - tn.val, cl));
}
}
return list;
}
public static void Run()
{
var st = new Solution99();
Console.WriteLine("Start: {0}", DateTime.Now);
/*
4
2 3
1 5
*/
var tn = new TreeNode(4);
tn.left = new TreeNode(2);
tn.right = new TreeNode(3);
tn.left.left = new TreeNode(1);
tn.left.right = new TreeNode(5);
st.RecoverTree(tn);
Util.PrintTreeNode(tn);
var tn2 = new TreeNode(0);
tn2.left = new TreeNode(1);
st.RecoverTree(tn2);
Util.PrintTreeNode(tn2);
Console.WriteLine("End: {0}", DateTime.Now);
}
public IList<IList<int>> LevelOrderUp(TreeNode root)
{
var q = new Queue<Tuple<TreeNode, int>>();
var list = new List<IList<int>>();
if (root == null)
return list;
q.Enqueue(new Tuple<TreeNode, int>(root, 0));
while(q.Count > 0)
{
var item = q.Dequeue();
var node = item.Item1;
var level = item.Item2;
if (node.left != null)
q.Enqueue(new Tuple<TreeNode, int>(node.left, level + 1));
if (node.right != null)
q.Enqueue(new Tuple<TreeNode, int>(node.right, level + 1));
if (list.Count <= level)
list.Add(new List<int>() { node.val });
else
list[level].Add(node.val);
}
return list;
}
TreeNode Recur(int[] inorder, int pb, int pe, Dictionary<int, int> map)
{
if (pb == pe)
return new TreeNode(inorder[pb]);
int min = map[inorder[pb]];
int pos = pb;
for(int i = pb+1; i<= pe; i++)
{
if (map[inorder[i]] < min)
{
min = map[inorder[pb]];
pos = i;
}
}
var tn = new TreeNode(inorder[pos]);
if (pos == pb)
tn.left = null;
else
{
tn.left = Recur(inorder, pb, pos-1, map);
}
if (pos == pe)
tn.right = null;
else
tn.right = Recur(inorder, pos + 1, pe, map);
return tn;
}
public bool Traverse(TreeNode root, int sum)
{
if (root == null)
{
return false;
}
/*代表是叶子节点*/
if (root.left == null && root.right == null)
{
pathSum = pathSum + root.val;
if (pathSum == sum)
return true;
else
{
pathSum = pathSum - root.val;
return false;
}
}
pathSum = pathSum + root.val;
/*如果左右节点都返回false，则将这个节点去除，并返回false*/
if (false == Traverse(root.left, sum) && false == Traverse(root.right, sum))
{
pathSum = pathSum - root.val;
return false;
}
else
{
return true;//左右节点只要有一个节点返回true，则就返回true
}
}
public static void Run()
{
var st = new Solution235();
TreeNode tn = new TreeNode(6);
TreeNode tn2 = new TreeNode(2);
TreeNode tn3 = new TreeNode(8);
TreeNode tn4 = new TreeNode(0);
TreeNode tn5 = new TreeNode(4);
TreeNode tn6 = new TreeNode(7);
TreeNode tn7 = new TreeNode(9);
tn4.left = tn4.right = null;
tn5.left = tn5.right = null;
tn6.left = tn6.right = null;
tn7.left = tn7.right = null;
tn.left = tn2;
tn.right = tn3;
tn2.left = tn4;
tn2.right = tn5;
tn3.left = tn6;
tn3.right = tn7;
Console.WriteLine("Start: {0}", DateTime.Now);
var re = st.LowestCommonAncestor(tn, tn5, tn7);
Console.WriteLine("{0}", re.val);
Console.WriteLine("End: {0}", DateTime.Now);
}
public static void Run()
{
var st = new Solution226();
Console.WriteLine("Start: {0}", DateTime.Now);
TreeNode tn = new TreeNode(1);
TreeNode tn2 = new TreeNode(2);
TreeNode tn3 = new TreeNode(3);
TreeNode tn4 = new TreeNode(4);
TreeNode tn5 = new TreeNode(5);
TreeNode tn6 = new TreeNode(6);
TreeNode tn7 = new TreeNode(7);
tn4.left = tn4.right = null;
tn5.left = tn5.right = null;
tn6.left = tn6.right = null;
tn7.left = tn7.right = null;
tn.left = tn2;
tn.right = tn3;
tn2.left = tn4;
tn2.right = tn5;
tn3.left = tn6;
tn3.right = tn7;
Util.PrintTreeNode(st.InvertTree(tn));
Console.WriteLine("End: {0}", DateTime.Now);
}
public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
{
Dictionary<TreeNode, List<TreeNode>> dict = new Dictionary<TreeNode, List<TreeNode>>();
Stack<TreeNode> st = new Stack<TreeNode>();
st.Push(root);
var lt = new List<TreeNode>();
lt.Add(root);
dict.Add(root, lt);
var pfound = false;
var qfound = false;
while(st.Count > 0)
{
TreeNode cur = st.Pop();
if (cur == p)
pfound = true;
if (cur == q)
qfound = true;
if (pfound && qfound)
break;
var curList = dict[cur];
if (cur.left != null)
{
var lnode = new List<TreeNode>();
lnode.AddRange(curList);
lnode.Add(cur.left);
dict.Add(cur.left, lnode);
st.Push(cur.left);
}
if (cur.right != null)
{
var rnode = new List<TreeNode>();
rnode.AddRange(curList);
rnode.Add(cur.right);
dict.Add(cur.right, rnode);
st.Push(cur.right);
}
}
var plist = dict[p];
var qlist = dict[q];
int i = 0;
for(; i< plist.Count() && i < qlist.Count(); i++)
{
if (plist[i] != qlist[i])
break;
}
if (i == plist.Count())
return p;
if (i == qlist.Count())
return q;
return plist[i - 1];
}
public IList<IList<int>> LevelOrder(TreeNode root)
{
var list = new List<IList<int>>();
Traverse(root, list, 0);
return list;
}
public bool IsSymmetric(TreeNode root)
{
if (root == null)
return true;
return Judge(root.left, root.right);
}
public bool IsValidBST(TreeNode root)
{
Stack<int> leftst = new Stack<int>();
Stack<int> rightst = new Stack<int>();
if (root == null)
return true;
return checkBST(root, leftst, rightst);
}
public BSTIterator(TreeNode root)
{
lt = new Stack<TreeNode>();
while(root != null)
{
lt.Push(root);
root = root.left;
}
}
public int MaxDepth(TreeNode root)
{
if (root == null)
return 0;
var left = MaxDepth(root.left) + 1;
var right = MaxDepth(root.right) + 1;
return left > right ? left : right;
}
public int MaxPathSum(TreeNode root)
{
if (root == null)
return 0;
int re = int.MinValue;
Recur(root, ref re);
return re;
}
public IList<IList<int>> PathSum2(TreeNode root, int sum)
{
List<IList<int>> list = new List<IList<int>>();
if (root == null)
return list;
PathFindSum(root, sum, list, new List<int>());
return list;
}
public IList<IList<int>> LevelOrderBottom(TreeNode root)
{
var list = LevelOrderUp(root);
var nlist = new List<IList<int>>();
for (int i = list.Count - 1; i >= 0; i--)
nlist.Add(list[i]);
return nlist;
}
public int MinDepth(TreeNode root)
{
int level = -1;
if (root == null)
return 0;
Traverse(root, 1, ref level);
return level;
}
public void Recur(TreeNode tn, int level, Dictionary<int, int> map)
{
if (tn.right != null)
Recur(tn.right, level + 1, map);
if (!map.ContainsKey(level))
map[level] = tn.val;
if (tn.left != null)
Recur(tn.left, level + 1, map);
}
public static void Run()
{
var st = new Solution129();
Console.WriteLine("Start: {0}", DateTime.Now);
TreeNode p = new TreeNode(1);
p.left = new TreeNode(2);
p.right = new TreeNode(3);
Console.WriteLine(st.SumNumbers(p));
Console.WriteLine("End: {0}", DateTime.Now);
}
public bool IsSameTree(TreeNode p, TreeNode q)
{
if (p == null && q == null)
return true;
if ((p == null && q != null) || (p != null && q == null))
return false;
if (p.val != q.val)
return false;
return IsSameTree(p.left, q.left) && IsSameTree(p.right, q.right);
}