-- author : coder_zhang
-- date   : 2014-6-25

root = nilfunction  insert_node(number)    if root == nil then        root = {value = http://www.mamicode.com/number, left = nil, right = nil, parent = nil}    else        q = root        r = nil        while q ~= nil do            r = q            if q.value > number then                q = q.left            elseif q.value < number then                q = q.right            else                return            end        end        if r.value > number then            r.left = {value = http://www.mamicode.com/number, left = nil, right = nil, parent = r}        else            r.right = {value = http://www.mamicode.com/number, left = nil, right = nil, parent = r}        end    endendfunction  find_node(p, number)     while p ~= nil do        if p.value =http://www.mamicode.com/= number then            return p        elseif p.value > number then            p = p.left        else            p = p.right        end    end    return pendfunction  delete_node(number)     p = find_node(root, number)    if p == nil then        print ("can\‘t find " .. number)        return    end    real_del = nil    if p.left == nil or p.right == nil then        real_del = p    else        q = p.right        r = nil        while q ~= nil do            r = q            q = q.left        end        real_del = r    end    child = nil    if real_del.left ~= nil then        child = real_del.left    else        child = real_del.right    end    if child ~= nil then       child.parent = real_del.parent    end    if real_del.parent == nil then        root = child    else        if real_del.parent.left == real_del then            real_del.parent.left = child        else            real_del.parent.right = child        end    end    if real_del ~= p then        p.value = real_del.value    end    real_del = nilendfunction  pre_order(p)    if p ~= nil then        print (p.value)        pre_order(p.left)        pre_order(p.right)    endendfunction  in_order(p)    if p ~= nil then        in_order(p.left)        print (p.value)        in_order(p.right)    endendfunction  post_order(p)    if p ~= nil then        post_order(p.left)        post_order(p.right)        print (p.value)    endendfunction  pre_order_no_rec(p)    stack = {}    while p ~= nil or #stack ~= 0 do        if p == nil then            p = stack[#stack]            stack[#stack] = nil        end        print (p.value)        if p.right ~= nil then            stack[#stack + 1] = p.right        end        p = p.left    endendfunction  in_order_no_rec(p)    stack = {}    while p ~= nil or #stack ~= 0 do        if p == nil then            p = stack[#stack]            stack[#stack] = nil            print (p.value)            p = p.right        else            stack[#stack + 1] = p            p = p.left        end    endendfunction  post_order_no_rec(p)     stack = {}    while p ~= nil do       stack[#stack + 1] = {node = p, status = 0}       p = p.left    end    while #stack ~= 0 do        p = stack[#stack]        if p.node.right == nil or p.status == 1 then            print (p.node.value)            stack[#stack] = nil        else            p = p.node.right            stack[#stack].status = 1            while p ~= nil do                stack[#stack + 1] = {node = p, status = 0}                p = p.left            end        end    endendarray = {5, 3, 2, 4, 7, 6, 8}i = 1while i <= #array do    insert_node(array[i])    i = i + 1endprint ("--------pre order---------")pre_order(root)print ("--------------------------")print ("-------in order-----------")in_order(root)print("---------------------------")print ("-------post order---------")post_order(root)print ("--------------------------")print ("-----pre order no rec-----")pre_order_no_rec(root)print ("--------------------------")print ("-----in order no rec------")in_order_no_rec(root)print ("--------------------------")print ("---post order no rec------")post_order_no_rec(root)print ("--------------------------")delete_node(3)pre_order(root)