c语言写一个红黑树代码

以下是一个简单的红黑树实现，包括插入节点、查找节点和删除节点的基本操作：

#include <stdio.h>
#include <stdlib.h>

enum Color {RED, BLACK};

typedef struct Node {
    int key;
    enum Color color;
    struct Node *left, *right, *parent;
} Node;

Node *root = NULL;

void rotate_left(Node *x) {
    Node *y = x->right;
    x->right = y->left;
    if (y->left != NULL) {
        y->left->parent = x;
    }
    y->parent = x->parent;
    if (x->parent == NULL) {
        root = y;
    }
    else if (x == x->parent->left) {
        x->parent->left = y;
    }
    else {
        x->parent->right = y;
    }
    y->left = x;
    x->parent = y;
}

void rotate_right(Node *x) {
    Node *y = x->left;
    x->left = y->right;
    if (y->right != NULL) {
        y->right->parent = x;
    }
    y->parent = x->parent;
    if (x->parent == NULL) {
        root = y;
    }
    else if (x == x->parent->right) {
        x->parent->right = y;
    }
    else {
        x->parent->left = y;
    }
    y->right = x;
    x->parent = y;
}

void insert_fixup(Node *z) {
    while (z->parent != NULL && z->parent->color == RED) {
        if (z->parent == z->parent->parent->left) {
            Node *y = z->parent->parent->right;
            if (y != NULL && y->color == RED) {
                z->parent->color = BLACK;
                y->color = BLACK;
                z->parent->parent->color = RED;
                z = z->parent->parent;
            }
            else {
                if (z == z->parent->right) {
                    z = z->parent;
                    rotate_left(z);
                }
                z->parent->color = BLACK;
                z->parent->parent->color = RED;
                rotate_right(z->parent->parent);
            }
        }
        else {
            Node *y = z->parent->parent->left;
            if (y != NULL && y->color == RED) {
                z->parent->color = BLACK;
                y->color = BLACK;
                z->parent->parent->color = RED;
                z = z->parent->parent;
            }
            else {
                if (z == z->parent->left) {
                    z = z->parent;
                    rotate_right(z);
                }
                z->parent->color = BLACK;
                z->parent->parent->color = RED;
                rotate_left(z->parent->parent);
            }
        }
    }
    root->color = BLACK;
}

void insert(int key) {
    Node *z = malloc(sizeof(Node));
    z->key = key;
    z->color = RED;
    z->left = NULL;
    z->right = NULL;
    z->parent = NULL;
    Node *y = NULL;
    Node *x = root;
    while (x != NULL) {
        y = x;
        if (key < x->key) {
            x = x->left;
        }
        else {
            x = x->right;
        }
    }
    z->parent = y;
    if (y == NULL) {
        root = z;
    }
    else if (key < y->key) {
        y->left = z;
    }
    else {
        y->right = z;
    }
    insert_fixup(z);
}

Node *tree_minimum(Node *x) {
    while (x->left != NULL) {
        x = x->left;
    }
    return x;
}

void transplant(Node *u, Node *v) {
    if (u->parent == NULL) {
        root = v;
    }
    else if (u == u->parent->left) {
        u->parent->left = v;
    }
    else {
        u->parent->right = v;
    }
    if (v != NULL) {
        v->parent = u->parent;
    }
}

void delete_fixup(Node *x) {
    while (x != root && x->color == BLACK) {
        if (x == x->parent->left) {
            Node *w = x->parent->right;
            if (w->color == RED) {
                w->color = BLACK;
                x->parent->color = RED;
                rotate_left(x->parent);
                w = x->parent->right;
            }
            if (w->left->color == BLACK && w->right->color == BLACK) {
                w->color = RED;
                x = x->parent;
            }
            else {
                if (w->right->color == BLACK) {
                    w->left->color = BLACK;
                    w->color = RED;
                    rotate_right(w);
                    w = x->parent->right;
                }
                w->color = x->parent->color;
                x->parent->color = BLACK;
                w->right->color = BLACK;
                rotate_left(x->parent);
                x = root;
            }
        }
        else {
            Node *w = x->parent->left;
            if (w->color == RED) {
                w->color = BLACK;
                x->parent->color = RED;
                rotate_right(x->parent);
                w = x->parent->left;
            }
            if (w->right->color == BLACK && w->left->color == BLACK) {
                w->color = RED;
                x = x->parent;
            }
            else {
                if (w->left->color == BLACK) {
                    w->right->color = BLACK;
                    w->color = RED;
                    rotate_left(w);
                    w = x->parent->left;
                }
                w->color = x->parent->color;
                x->parent->color = BLACK;
                w->left->color = BLACK;
                rotate_right(x->parent);
                x = root;
            }
        }
    }
    x->color = BLACK;
}

void delete(int key) {
    Node *z = root;
    while (z != NULL) {
        if (key == z->key) {
            break;
        }
        else if (key < z->key) {
            z = z->left;
        }
        else {
            z = z->right;
        }
    }
    if (z == NULL) {
        return;
    }
    Node *y = z;
    enum Color y_original_color = y->color;
    if (z->left == NULL) {
        Node *x = z->right;
        transplant(z, z->right);
        free(z);
        if (x != NULL) {
            delete_fixup(x);
        }
    }
    else if (z->right == NULL) {
        Node *x = z->left;
        transplant(z, z->left);
        free(z);
        if (x != NULL) {
            delete_fixup(x);
        }
    }
    else {
        y = tree_minimum(z->right);
        y_original_color = y->color;
        Node *x = y->right;
        if (y->parent == z) {
            if (x != NULL) {
                x->parent = y;
            }
        }
        else {
            transplant(y, y->right);
            y->right = z->right;
            y->right->parent = y;
        }
        transplant(z, y);
        y->left = z->left;
        y->left->parent = y;
        y->color = z->color;
        free(z);
        if (x != NULL) {
            delete_fixup(x);
        }
    }
}

void inorder_traversal(Node *x) {
    if (x != NULL) {
        inorder_traversal(x->left);
        printf("%d ", x->key);
        inorder_traversal(x->right);
    }
}

Node *search(int key) {
    Node *x = root;
    while (x != NULL) {
        if (key == x->key) {
            return x;
        }
        else if (key < x->key) {
            x = x->left;
        }
        else {
            x = x->right;
        }
    }
    return NULL;
}

int main() {
    insert(10);
    insert(20);
    insert(30);
    insert(15);
    insert(18);
    insert(25);
    insert(40);
    inorder_traversal(root);
    printf("\n");
    delete(20);
    inorder_traversal(root);
    printf("\n");
    Node *x = search(15);
    if (x != NULL) {
        printf("%d\n", x->key);
    }
    return 0;
}

注：此红黑树实现没有考虑内存泄漏的情况。