好的，对于这个项目，我们必须在C中给出函数快速排序，这是C
中的函数void quickSort ( int arr [], int left , int right ) {
int index = partition (arr , left , right );
if ( left < index - 1) {
quickSort (arr , left , index - 1);
}
if ( index < right ) {
quickSort (arr , index , right );
}
}
int partition ( int arr [], int left , int right ) {
int i = left , j = right ;
int tmp;
int pivot = arr [( left + right ) / 2];
while (i <= j) {
while (arr[i] < pivot ) {
i++;
}
while (arr[j] > pivot ) {
j --;
}
if (i <= j) {
tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
i++;
j --;
}
}
return i;
}
这是我在MIPS中的功能
.data
out: .asciiz "The elements sorted in ascending order are: " #for printing output
comma: .asciiz ", " #for commma between numbers in output
arr: .space 80 #space for 20 elements in array
.text
Main: addi $v0, $zero, 5 #set up for reading input(array size)
syscall #read integer
add $s0, $zero, $v0 #$s0 = the size of the array the user entered
la $s1, arr #$s1 = base address of array
addi $t0, $s0, 0 #$t0 = size of array for looping condition
add $t2, $zero, $s1 #$t2 = base adress array for loop
LoopIns: beq $t0, $zero, InsE #when $t0 gets to 0 all elements have been added, end loop
addi $v0, $zero, 5 #set up for reading integer(to insert into array)
syscall #read integer
addi $t1, $v0, 0 #store integer read in t1
sw $t1, 0($t2) #store integer read into array
addi $t2, $t2, 4 #$t2(arraybase address) = $t2 + 4
subi $t0, $t0, 1 #decrement looping condition(array size)
j LoopIns #jump back to top of loop
InsE: subi $t3, $s0, 1 #$t3 = array size - 1(right)
add $a0, $zero, $s1 #$a0 = base adress array(int arr[])
addi $a1, $zero, 0 #$a1 = 0(left)
add $a2, $zero, $t3 #$a2 = $t3(right)
jal quickSort #run quick sort
la $a0, out #load address of output start
addi $v0, $zero, 4 #set up for printing string
syscall #print string
addi $t4, $s0, 0 #size of array for looping condition
addi $t5, $s1, 0 #$t3 = arrray base address
PrintLoop: beq $t4, $zero, PrintLoopEnd #if array size get to 0 all elements have printed, end loop
lw $t6, 0($t5) #t6 = arr[index]
addi $a0, $t6, 0 #$a0 = arr[index] to print
addi $v0, $zero, 1 #set up $v0 to print integer
syscall
beq $t4, 1, endCom #if array size == 1, dont print comma
la $a0, comma #$a0 = comma to print
addi $v0, $zero, 4 #set up v0 for printing string
syscall
endCom: addi $t5, $t5, 4 #$t3 = next index in array
subi $t4, $t4, 1 #decrement looping condition(array size)
j PrintLoop #repeat printing loop
PrintLoopEnd: addi $v0, $zero, 10 #set up $v0 for clean exit
syscall #exit program
#------------------------------------------------------------------------------------------------------------------------
quickSort: addi $sp, $sp, -16 #make room on stack
sw $a1, 12($sp) #save $a1 on stack
sw $a2, 8($sp) #save $a2 on stack
sw $s0, 4($sp) #save $s0 on stack
sw $ra, 0($sp) #save $ra on stack
jal partition #jump to partition
addi $s0, $v0, 0 #index = partition(arr, left, right)
subi $t0, $s0, 1 #$t0 = index - 1
IfFirst: slt $t1, $a1, $t0 #$t1 = (left < index - 1) ? 1 : 0
beq $t1, $zero, IfSecond # !(left < index - 1) ? 1 : 0
addi $a2, $s0, -1 #$a2 = index - 1
jal quickSort #quickSort(arr, left, index - 1) #jump to return
IfSecond: slt $t2, $s0, $a2 #$t2 = (index < right) ? 1 : 0
beq $t2, $zero, QuickSortRET # !(index < right) --> IfSecondEnd
addi $a1, $s0, 0 #$a1 = index
jal quickSort #quickSort(arr, index, right)
QuickSortRET: lw $a1, 12($sp) #restore $a1
lw $a2, 8($sp) #restore $a2
lw $s0, 4($sp) #restore $s0
lw $ra, 0($sp) #restore $ra
addi $sp, $sp, 16 #pop stack
jr $ra #return to caller
#--------------------------------------------------------------------------------------------------------------------------
partition: addi $sp, $sp, -16 #make room on stack
sw $s0, 12($sp) #store $s0 on stack
sw $s1, 8($sp) #store $s1 on stack
sw $s2, 4($sp) #store $s2 on stack
sw $s3, 0($sp) #store $s3 on stack
add $s0, $zero, $a1 #i($s0) = left
add $s1, $zero, $a2 #j($s1) = right
add $t0, $a1, $a2 #$t0 = left + right
srl $t0, $t0, 1 #$t0 = (left + right)/2
sll $t0, $t0, 2 #$t0 = ((left + right)/2) * 4
add $t0, $a0, $t0 #$t0 = address + (((left + right)/2) * 4)
lw $t0, 0($t0) #$t0 = arr[(left + right) / 2]
addi $s3, $t0, 0 #pivot = arr[(left + right) / 2]
OuterWhile: slt $t0, $s1, $s0 #$t0 = (j < i) ? 1 : 0
bne $t0, $zero, OuterWhEnd
InnerWhile1: add $t1, $zero, $s0 #$t1 = i
sll $t1, $t1, 2 #$t1 = i * 4
add $t1, $a0, $t1 #$t1 = addr + (i * 4)
lw $t1, 0($t1) #$t1 = arr[i]
slt $t2, $t1, $s3 #$t2 = (arr[i] < pivot) ? 1 : 0
beq $t2, $zero, InnerWhile2 #!(arr[i] < pivot) --->InnerWhile1End
addi $s0, $s0, 1 #i = i + 1
j InnerWhile1 #jump back to top of loop
InnerWhile2: add $t3, $zero, $s1 #$t3 = j
sll $t3, $t3, 2 #$t3 = j * 4
add $t3, $a0, $t3 #$t3 = address + (j * 4)
lw $t3, 0($t3) #$t3 = arr[j]
slt $t4, $s3, $t3 #$t4 = (pivot < arr[j]) ? 1 : 0
beq $t4, $zero, OuterIfStart # !(pivot < arr[j]) --->InnerWhile2End
subi $s1, $s1, 1 #j = j - 1
j InnerWhile2 #jump back to top of loop
OuterIfStart: slt $t2, $s1, $s0 #$t2 = (j < i) ? 1 : 0
bne $t2, $zero, LoopR # !(j < i) ---> OuterIfEnd
add $t1, $zero, $s0 #$t1 = i
sll $t1, $t1, 2 #$t1 = i * 4
add $t1, $a0, $t1 #$t1 = address + (i * 4)
lw $t3, 0($t1) #$t3 = arr[i]
add $t4, $zero, $s1 #$t4 = j
sll $t4, $t4, 2 #$t4 = j * 4
add $t4, $a0, $t4 #$t4 = address + (j * 4)
lw $t5, 0($t4) #$t5 = arr[j]
add $s2, $zero, $t3 #tmp = arr[i]
sw $t5, 0($t1) #arr[i] = arr[j]
sw $s2, 0($t4) #arr[j] = tmp
addi $s0, $s0, 1 #i = i + 1
subi $s1, $s1, 1 #j = j - 1
LoopR: j OuterWhile
OuterWhEnd: addi $v0, $s0, 0 #v0 = i
lw $s0, 12($sp) #restore $s0 on stack
lw $s1, 8($sp) #restore $s1 on stack
lw $s2, 4($sp) #restore $s2 on stack
lw $s3, 0($sp) #restore $s3 on stack
addi $sp, $sp, 16 #pop stack
jr $ra
每当我在输入7（数组大小）上运行程序，然后是2,5,1，-7,2,4,16时，只返回一些数组。我得到的输出是-7,1,2,2,5,4,16。只有一个元素乱序，我无法通过查看我的代码找出原因。如果有人能帮助我理解为什么这样做会很棒，谢谢。
答案 0 :(得分：0)
简单地说，使用 do while 循环代替 while 循环可以解决问题。