關於紅黑樹的理論講解，網上有很多，大家可以自己找，這裡重點在於實現，程式碼供大家參考。程式碼如下：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#define RED     0
#define BLACK   1
#define NUM     9

typedef struct RBTNode
{
    int key;
    struct RBTNode *parent,*left,*right;
    int color;
}RBTNode,*RBTree;

RBTree nil,root;

void InitLeafNode()
{
    nil =(RBTree)malloc(sizeof(RBTree));
    root=(RBTree)malloc(sizeof(RBTree));
    nil->color      = BLACK;
    nil->left       = NULL;
    nil->right      = NULL;
    nil->key        = -1;
    root            = nil;
}

RBTree CreatNode(int key,int color)
{
    RBTree x;
    x=(RBTNode *)malloc(sizeof(RBTNode));
    x->color        = color;
    x->key          = key;
    x->left         = nil;
    x->right        = nil;
    x->parent       = NULL;
    return x;
}
void LeftRotate(RBTree z)                  //左旋
{
    RBTree y;
    y = z->right;
    z->right = y->left;             //set y
    if(y->left != nil)
        y->left->parent = z;
    y->parent = z->parent;

    if(z->parent == nil)
        root = y;
    else if(z == z->parent->left)
        z->parent->left 	= y;
    else
        z->parent->right	= y;
    //Put z on y's left.
    y->left     = z;
    z->parent   = y;
}
void RightRotate(RBTree z)      //右旋
{
    RBTree y;
    y = z->left;
    z->left = y->right;
    if(y->right != nil)
        y->right->parent = z;
    y->parent = z->parent;
    if(z->parent == nil)
        root = y;
    else if(z == z->parent->left)
        z->parent->left     = y;
    else
        z->parent->right    = y;
    y->right  = z;
    z->parent = y;
}
void TreeInsert(RBTree z)     //插入
{
    RBTree x,y;
    y = nil;
    x = root;
    while(x!=nil){         //Find the insertion position.
        y = x;
        if(z->key<x->key)
            x = x->left;
        else
            x = x->right;
    }
    z->parent = y;
    if(y == nil)
        root = z;
    else{
        if(z->key < y->key)
            y->left  = z;
        else
            y->right = z;
    }
}
void RBTreeInsertFixup(RBTree z)       //維護
{
    RBTree y;
    while(z->parent->color == RED){
        if(z->parent == z->parent->parent->left){
            y = z->parent->parent->right;
            if(y->color == RED){						//case 1.
                z->parent->color         = BLACK;
                z->parent->parent->color = RED;
                y->color                 = BLACK;
                z = z->parent->parent;
            }
            else{
                if(z == z->parent->right){					//case 2.
                    z = z->parent;
                    LeftRotate(z);
                }
                z->parent->color            = BLACK;		           	//case 3.
                z->parent->parent->color    = RED;
                z                           = z->parent->parent;
                RightRotate(z);
            }
        }
        else{                                //symmetry of (case 1,2,3)
            y = z->parent->parent->left;
            if(y->color == RED){
                z->parent->color         =BLACK;
                z->parent->parent->color =RED;
                y->color                 =BLACK;
                z = z->parent->parent;
            }
            else{
                if(z == z->parent->left){
                    z = z->parent;
                    RightRotate(z);
                }
                z->parent->color 		= BLACK;
                z->parent->parent->color 	= RED;
                z                           	= z->parent->parent;
                LeftRotate(z);
            }
        }
    }
    root->color = BLACK;
}
void RBTreeInsert(RBTree z)
{
    TreeInsert(z);
    z->left  = nil;
    z->right = nil;
    //z->color = RED;
    RBTreeInsertFixup(z);
}

int main(void)
{
    RBTree node[NUM];
    int key;
    int i;
    int A[NUM]={8,11,17,15,6,1,22,25,27};
    InitLeafNode();

    for(i=0;i<NUM;i++){
        key=A[i];
        node[i]=CreatNode(key,RED);
        RBTreeInsert(node[i]);
    }

    //驗證的時候就是列印每個節點的左孩子和右孩子的key，key為-1代表為葉子節點。 
    printf("The RBT is :\n");
    for(i=0;i<NUM;i++)
        printf("%d + %d\n",node[i]->left->key,node[i]->right->key);

    return 0;
}