红黑树的删除
以下是红黑树删除的伪代码：
RB-DELETE(T, z)
1 if left[z] = nil[T] or right[z] = nil[T]
2 then y ← z
3 else y ← TREE-SUCCESSOR(z)
4 if left[y] ≠ nil[T]
5 then x ← left[y]
6 else x ← right[y]
7 p[x] ← p[y]
8 if p[y] = nil[T]
9 then root[T] ← x
10 else if y = left[p[y]]
11 then left[p[y]] ← x
12 else right[p[y]] ← x
13 if y 3≠ z
14 then key[z] ← key[y]
15 copy y's satellite data into z
16 if color[y] = BLACK
17 then RB-DELETE-FIXUP(T, x)
18 return y
RB-DELETE-FIXUP(T, x)
1 while x ≠ root[T] and color[x] = BLACK
2 do if x = left[p[x]]
3 then w ← right[p[x]]
4 if color[w] = RED
5 then color[w] ← BLACK ▹ Case 1
6 color[p[x]] ← RED ▹ Case 1
7 LEFT-ROTATE(T, p[x]) ▹ Case 1
8 w ← right[p[x]] ▹ Case 1
9 if color[left[w]] = BLACK and color[right[w]] = BLACK
10 then color[w] ← RED ▹ Case 2
11 x ← p[x] ▹ Case 2
12 else if color[right[w]] = BLACK
13 then color[left[w]] ← BLACK ▹ Case 3
14 color[w] ← RED ▹ Case 3
15 RIGHT-ROTATE(T, w) ▹ Case 3
16 w ← right[p[x]] ▹ Case 3
17 color[w] ← color[p[x]] ▹ Case 4
18 color[p[x]] ← BLACK ▹ Case 4
19 color[right[w]] ← BLACK ▹ Case 4
20 LEFT-ROTATE(T, p[x]) ▹ Case 4
21 x ← root[T] ▹ Case 4
22 else ▹ same as then clause with "right" and "left" exchange
w ← left[p[x]]
if color[w] = RED
then color[w] ← BLACK ▹ Case 5
color[p[x]] ← RED ▹ Case 5
RIGHT-ROTATE(T, p[x]) ▹ Case 5
w ← left[p[x]] ▹ Case 5
if color[right[w]] = BLACK and color[left[w]] = BLACK
then color[w] ← RED ▹ Case 6
x ← p[x] ▹ Case 6
else if color[left[w]] = BLACK
then color[right[w]] ← BLACK ▹ Case 7
color[w] ← RED ▹ Case 7
LEFT-ROTATE(T, w) ▹ Case 7
w ← left[p[x]] ▹ Case 7
color[w] ← color[p[x]] ▹ Case 8
color[p[x]] ← BLACK ▹ Case 8
color[left[w]] ← BLACK ▹ Case 8
RIGHT-ROTATE(T, p[x]) ▹ Case 8
x ← root[T] ▹ Case 8
23 color[x] ← BLACK