我正在做关于 MIPS 的作业，任务是在 MIPS 中创建一个二叉树，它可以接受双精度浮点数并动态分配空间。有没有人可以使用 MIPS 中的二叉树示例？
【问题讨论】：
标签： binary-tree mips
如果您知道如何在 MIPS 中创建数组，您可以将二叉树投影到数组上。它或多或少会浪费大量空间，但它会半简单地工作。
首先确定您将如何在堆栈上组织内存中的节点。我会组织它：
[data to store] #presumably floating point numbers
[address of left node]
[address of right node]
为节点指定一个空值，可能是0x7ff...f
指定一个空地址，可能是0
创建一个大小为 : (2^n - 1) * NodeSize
的数组
其中 n = 树的最深分支的深度，从 1 开始计数，而不是 0。NodeSize 是描述节点所需的单词数。
数组的索引将与下面描述的模式相对应。
0
/ \
1 2
/ \ / \
3 4 5 6
使用起来会有些困难，但应该可以。我想从技术上讲，如果你管理好树，你不需要数组来索引空值，或者如果你保持我描述的格式，你真的不需要保存其他节点的地址，因为它们是由他们的索引暗示。所以真的你只需要一个或另一个。你真的应该通过弄清楚你想要使用多少地址以及你的树有多满来选择哪一个更容易。如果您的树已满，则隐含的边有助于节省空间。
tl;dr 这将通过两种方式描述树来浪费空间。删除数组创意或地址。
【讨论】：
我有一个类似的项目。
我的解决方案如下：
##################################################
#
# Binary Search Tree - Project 1
#
# First Assembly Program :)
#
##################################################
.data
nl: .asciiz "\n"
prompt1: "\nPlease select an option from the list below:\n"
prompt2: "[A] - Add a record to the tree\n"
prompt3: "[F] - Find a record in the tree\n"
prompt4: "[P] - Perform a preorder traversal\n"
prompt5: "[I] - Perform an inorder traversal\n"
prompt6: "[Q] - Quit the program\n"
prompt7: "\nChoose a character: "
empty: "\nThe Tree is Empty."
youentered: "\nYou Entered: "
recordfound: "\nRecord Found: "
recordnotfound: "\nRecord Not Found! "
goodbye: "\nGoodbye!"
addid: "\nEnter the ID to add: "
addyear: "Enter the year: "
addtitle: "Enter the title: "
adddescription: "Enter the description: "
id: "\nID: "
year: "\nYear: "
title: "\nTitle: "
description: "Description: "
#idsize: .word 0
#optiona: 97 addrecord a
#optionf: 102 findrecord f
#optionp: 112 preorder p
#optioni: 105 inorder i
#optionq: 113 quit q
###################################################################
#
# Note: I reuse a lot of print statements
# This code is far from what I would call optimized
#
# This is my first assembly program and I'm really just
# Happy to see it all working :)
#
# I spent about 18 hours writing this so lol :)
#
# The only thing that I've gotten to crash it so far is
# Entering characters when it's waiting for an int :)
#
######################################################
#
# Here is my memory setup:
#
# $s5 - Stores Root Node
# $s7 - Stores Size of Tree (Not Really Necessary)
#
# Each New Item Contains a chunk of 344 bytes
# The bytes are setup as such:
#
# 8 Bytes - [ID]
# 8 Bytes - [Year]
# 64 Bytes - [Title]
# 256 Bytes - [Description]
# 8 Bytes - [LeftNodeAddress]
# 8 Bytes - [RightNodeAddress]
#
#
# Example Tree:
#
# 10 -Root
# / \
# 7 15 -Branch
# / \ / \
# 6 9 12 17 -Leaf
#
# In Memory:
#
# [Offset: 328] - [ID] - [Offset: 336]
# | |
# [Off: 328][ID][Off:336] [Off: 328][ID][Off: 336] . . .
#
#
########################################################
.text
###################
##Prompt Function##
###################
prompt:
li $v0, 4
la $a0, prompt1 #Please select an option from the list below:
syscall
li $v0, 4
la $a0, prompt2 #[A] - Add a record to the tree
syscall
li $v0, 4
la $a0, prompt3 #[F] - Find a record in the tree
syscall
li $v0, 4
la $a0, prompt4 #[P] - Preorder traversal
syscall
li $v0, 4
la $a0, prompt5 #[I] - Inorder traversal
syscall
li $v0, 4
la $a0, prompt6 #[Q] - Quit the program
syscall
###################
##Get User Input ##
###################
getinput:
li $v0, 4 #Choose a character:
la $a0, prompt7
syscall
li $v0, 12 #Read a single character from console
syscall
move $s0, $v0
beq $s0, 97, addrecord #If you press 'a', addrecord
beq $s0, 102, findrecord #If you press 'f', findrecord
beq $s0, 112, preorder #If you press 'p', preorder
beq $s0, 105, inorder #If you press 'i', inorder
beq $s0, 113, exit #If you press 'q', exit
li $v0, 4 #If you press something random
la $a0, nl #Display new line
syscall
j getinput #And ask for a new character
###################
## Add A Record ##
###################
addrecord:
li $v0, 9 #allocate memory for new record
li $a0, 344 #enough memory for 2 addresses and all the data
syscall
move $s0, $v0 #hang onto the initial address of all our info
li $v0, 4 #prompt for ID
la $a0, addid
syscall
li $v0, 5 #enter integer
syscall
sw $v0, 0($s0) #store our ID into memory Offset: 0
li $v0, 4 #prompt for add year
la $a0, addyear
syscall
li $v0, 5 #enter integer
syscall
sw $v0, 4($s0) #store year into our memory Offset: 4
li $v0, 4 #prompt for add title
la $a0, addtitle
syscall
li $v0, 8 #read our title into the allocated space
la $a0, 8($s0) #Offset: 8
li $a1, 64
syscall
li $v0, 4 #prompt for add description
la $a0, adddescription
syscall
li $v0, 8 #read our description into the allocated space
la $a0, 72($s0) #Offset: 72
li $a1, 256
syscall
bne $s7, 0, setlocations #if this isn't root node let's set the locations
add $s7, $s7, 1 #add 1 to the size of the records
move $s5, $s0 #store this address as root node for now
j prompt
########################
##Set Memory Locations##
########################
setlocations:
move $s6, $s5 #Keep $s5 as our root and use $s6 as temporary storage
move $s4, $s6 #Use $s4 to find the null node slot
storelocations:
beqz $s4, store #If we've reached a leaf, store
lw $t2, 0($s4) #get ID from current node
lw $t1, 0($s0) #get Current ID from new node node we're adding
ble $t1,$t2,goleft #get left location if new node <= current node
move $s6, $s4
lw $s4, 336($s4) #get node to the right if new node > current node
li $t3, 336 #be ready to store to the right slot
j storelocations
goleft:
move $s6, $s4
lw $s4, 328($s4) #load the node to the left
li $t3, 328 #be ready to store to the left slot
j storelocations
store:
beq $t3, 336, storeright #if $t3 was set to storeRight, then store to the right
sw $s0, 328($s6) #else store the new node's location into our node's left slot
add $s7, $s7, 1 #remind our size register that it's growing
j prompt #back to the prompt
storeright:
sw $s0, 336($s6) #store new node to the right slot
j prompt #back to the prompt
########################
## Find Record by ID ##
########################
findrecord:
move $s6, $s5
bne $s7, 0, search
li $v0, 4 #if tree is empty
la $a0, empty #display message Tree is empty
syscall
j prompt #and go wait for input
search:
move $s6, $s5
li $v0, 4 #print ID:
la $a0, id
syscall
li $v0, 5 #let user enter ID
syscall
move $t1, $v0 #store the id we're looking for in $t1
checkagain:
lw $t2, ($s6) #store the id we're currently looking at
bne $t1, $t2, checkempty #if this isn't the right ID, is it the last one?
###########################
##If we find the record:
###########################
li $v0, 4
la $a0, recordfound #Record Found:
syscall
li $v0, 4 #Print ID:
la $a0, id
syscall
li $v0, 1 #Print the ID stored at $s6 [Offset: 0]
lw $a0, 0($s6)
syscall
li $v0, 4 #Print Year:
la $a0, year
syscall
li $v0, 1 #Print the Year stored at $s6 [Offset: 4]
lw $a0, 4($s6)
syscall
li $v0, 4 #Print Title:
la $a0, title
syscall
li $v0, 4 #Print the Title stored at $s6 [Offset: 8]
la $a0, 8($s6)
syscall
li $v0, 4 #Print Description:
la $a0, description
syscall
li $v0, 4 #Print descript stored at $s6 [Offset: 72]
la $a0, 72($s6)
syscall
j getinput
checkempty:
ble $t1, $t2, checkleft #If $t1 <= $t2 check the left node
lw $s6, 336($s6) #Otherwise check the right node
bne $s6, 0, checkagain #If this record isn't empty, check again
li $v0, 4 #Otherwise
la $a0, recordnotfound #Record not found
syscall
j getinput
checkleft:
lw $s6, 328($s6) #Check the left node
bne $s6, 0, checkagain #If the record isn't empty, check again
li $v0, 4 #Otherwise
la $a0, recordnotfound #Record not found
syscall
j getinput
treeempty:
li $v0, 4 #if tree is empty
la $a0, empty #display message Tree is empty
syscall
j prompt
#####################################
#
# The Inorder Function
#
#####################################
inorder:
beq $s7, 0, treeempty #If the tree is empty display empty message
move $s6, $s5 #$s6 is the record we're currently at
move $t0, $s6 #t0 will iterate $s6 is our starting node
move $t1, $t0 #t1 will be thrown on the stack to keep track of everything
jal printinorder
j prompt
printinorder:
addi $sp, $sp, -12 #allocate 8 bytes for the stack
sw $ra, 0($sp) #4 for the $ra variable
sw $t1, 4($sp) #4 for $t1
bne $t0, 0, dontreturn #if $t0 isn't null don't return
lw $ra, 0($sp) #otherwise:
lw $t1, 4($sp) #pop stack
addi $sp, $sp, 12 #and prepare
jr $ra #to return
dontreturn:
move $t1, $t0 #put $t0 in $t1
lw $t0, 328($t0) #load the next pointer to the left
jal printinorder #and recurse back to printorder
move $s6, $t1 #if we're back here, it's time to print
j goprint #so go print
afterprint:
move $t0, $t1 #after we print, move $t1 back to $t0
lw $t0, 336($t0) #get the next pointer to the right
jal printinorder #recurse to see if it's the last one
move $s6, $t1 #if we made it here, it is, let's print
beq $s6, $t1, done #if we already printed this one, we're done (Root Node)
j goprint #Go print the node to the right
done:
lw $ra, 0($sp) #if we're done, pop our stack
lw $t1, 4($sp) #clean it up
addi $sp, $sp, 12 #8 bytes worth
jr $ra #and return
goprint:
li $v0, 4 #Print ID:
la $a0, id
syscall
li $v0, 1 #Print the ID stored at $s6 [Offset: 0]
lw $a0, 0($s6)
syscall
li $v0, 4 #Print Year:
la $a0, year
syscall
li $v0, 1 #Print the Year stored at $s6 [Offset: 4]
lw $a0, 4($s6)
syscall
li $v0, 4 #Print Title:
la $a0, title
syscall
li $v0, 4 #Print the Title stored at $s6 [Offset: 8]
la $a0, 8($s6)
syscall
li $v0, 4 #Print Description:
la $a0, description
syscall
li $v0, 4 #Print descript stored at $s6 [Offset: 72]
la $a0, 72($s6)
syscall
j afterprint
#####################################
#
# The Preorder Function
#
#####################################
preorder:
beq $s7, 0, treeempty #If the tree is empty display empty message
move $s6, $s5 #$s6 is the record we're currently at
move $t0, $s6 #t0 will iterate $s6 is our starting node
move $t1, $t0 #t1 will be thrown on the stack to keep track of everything
jal printpreorder
j prompt
printpreorder:
addi $sp, $sp, -12 #allocate 8 bytes for the stack
sw $ra, 0($sp) #4 for the $ra variable
sw $t1, 4($sp) #4 for $t1
bne $t0, 0, dontreturnpo #if $t0 isn't null don't return
lw $ra, 0($sp) #otherwise:
lw $t1, 4($sp) #pop stack
addi $sp, $sp, 12 #and prepare
jr $ra #to return
dontreturnpo:
move $s6, $t0 #if we made it here, it is, let's print
j goprintpo #so go print
afterprintpo:
move $t1, $t0 #put $t0 in $t1
lw $t0, 328($t0) #load the next pointer to the left
jal printpreorder #and recurse back to printorder
move $t0, $t1 #after we print, move $t1 back to $t0
lw $t0, 336($t0) #get the next pointer to the right
jal printpreorder #recurse to see if it's the last one
donepo:
lw $ra, 0($sp) #if we're done, pop our stack
lw $t1, 4($sp) #clean it up
addi $sp, $sp, 12 #8 bytes worth
jr $ra #and return
goprintpo:
li $v0, 4 #Print ID:
la $a0, id
syscall
li $v0, 1 #Print the ID stored at $s6 [Offset: 0]
lw $a0, 0($s6)
syscall
li $v0, 4 #Print Year:
la $a0, year
syscall
li $v0, 1 #Print the Year stored at $s6 [Offset: 4]
lw $a0, 4($s6)
syscall
li $v0, 4 #Print Title:
la $a0, title
syscall
li $v0, 4 #Print the Title stored at $s6 [Offset: 8]
la $a0, 8($s6)
syscall
li $v0, 4 #Print Description:
la $a0, description
syscall
li $v0, 4 #Print descript stored at $s6 [Offset: 72]
la $a0, 72($s6)
syscall
j afterprintpo
exit:
li $v0, 4 #Say
la $a0, goodbye #Goodbye!
syscall
li $v0, 10 #Terminate Program
syscall
【讨论】：