利用Lua实现二叉查找树并进行各种遍历

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

root = nil

function  insert_node(number)
if root == nil then
root = {value = 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 = number, left = nil, right = nil, parent = r}
else
r.right = {value = number, left = nil, right = nil, parent = r}
end
end
end

function  find_node(p, number)
while p ~= nil do
if p.value == number then
return p
elseif p.value > number then
p = p.left
else
p = p.right
end
end
return p
end

function  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 = nil
end

function  pre_order(p)
if p ~= nil then
print (p.value)
pre_order(p.left)
pre_order(p.right)
end
end

function  in_order(p)
if p ~= nil then
in_order(p.left)
print (p.value)
in_order(p.right)
end
end

function  post_order(p)
if p ~= nil then
post_order(p.left)
post_order(p.right)
print (p.value)
end
end

function  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
end
end

function  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
end
end

function  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
end
end

array = {5, 3, 2, 4, 7, 6, 8}

i = 1

while i <= #array do
insert_node(array[i])
i = i + 1
end

print ("--------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)