Language: C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct node{
  int key;
  struct node *parent;
  struct node *left;
  struct node *right;
}node;
typedef node * NodePointer;
NodePointer root, nil;
NodePointer make(int key, NodePointer p){
  NodePointer n;
  n = malloc(sizeof(struct node));
  n->key = key;
  n->parent = p;
  n->left = p;
  n->right = p;
  return n;
}

void insert(int key){
  NodePointer n, x, z;
  z = make(key, nil);
  n = root;
  x = nil;
  while(n != nil){
    x = n;
    if(n->key < key) n = n->right;
    else n = n->left;
  }
  z->parent = x;
  if(x == nil) root = z;
  if(x->key < z->key) x->right = z;
  if(x->key > z->key) x->left = z;
}
void find(NodePointer T, int key){
  if(T == nil){
    printf("no\n");
    return;
  }
  else if(T->key == key){
    printf("yes\n");
    return ;
  }
  else if(T->key < key) find(T->right, key);
  else if(T->key > key) find(T->left, key);
  return ;
}
void delete(NodePointer T, int key){
  NodePointer x, y;
  while(T->key != key){
    if(T->key < key) find(T->right, key);
    else if (T->key > key) find(T->left, key);
  }
  if(T->left == nil && T->right == nil)
    y = T;
  else
    y = Successor(T);
  if(y->left != nil)
    x = y->left;
  else
    x = y->right;
  if(x != nil)
    x->parent = y->parent;
  if(y->parent == nil)
    root = x;
  else if(y == y->parent->left)
    y->parent->left = x;
  else
    y->parent->right = x;
  if(y != T){
    T->key = y->key;
    T = y;
  }
}
NodePointer Successor(NodePointer T){
  NodePointer y;
  if(T->right != nil){
    while(T->left != nil){
      T = T->left;
    }
    return T;
  }
  y = T->parent;
  while(y != nil && T == y->right){
    T = y;
    y = y->parent;
  }
  return y;
}
void inorder(NodePointer T){
  if(T->left->key != 0) inorder(T->left);
  printf(" %d",T->key);
  if(T->right->key != 0) inorder(T->right);
}
void preorder(NodePointer T){
  printf(" %d",T->key);
  if(T->left != nil) preorder(T->left);
  if(T->right != nil) preorder(T->right);
}
void fre(NodePointer T){
  free(T);
  if(T->left != nil) fre(T->left);
  if(T->right != nil) fre(T->right);
}
int main(){
  int i ,n, key;
  char s[20];
  nil = make(0, nil);
  root = make(0, nil);
  root = nil;
  scanf("%d",&n);
  for(i = 0; i < n; i++){
    scanf("%s", s);
    if(s[0] == 'i'){
      scanf("%d",&key);
      insert(key);
    }
    else if(s[0] == 'd'){
      scanf("%d",&key);
      delete(root, key);
    }
    else if(s[0] == 'f'){
      scanf("%d",&key);
      find(root, key);
    }
    else if(s[0] == 'p'){
      inorder(root);
      printf("\n");
      preorder(root);
      printf("\n");  
    }
  }
  fre(root);
  free(nil);
  return 0;
}

Compiler output:
main.c: In function 'delete':
main.c:59:9: error: implicit declaration of function 'Successor' [-Wimplicit-function-declaration]
   59 |     y = Successor(T);
      |         ^~~~~~~~~
main.c:59:7: error: assignment to 'NodePointer' {aka 'node *'} from 'int' makes pointer from integer without a cast [-Wint-conversion]
   59 |     y = Successor(T);
      |       ^
main.c: At top level:
main.c:77:13: error: conflicting types for 'Successor'; have 'node *(node *)'
   77 | NodePointer Successor(NodePointer T){
      |             ^~~~~~~~~
main.c:59:9: note: previous implicit declaration of 'Successor' with type 'int()'
   59 |     y = Successor(T);
      |         ^~~~~~~~~