Size Balance Tree

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define Max_N 200000
#define size(_) ((_)==NULL ? 0 :(_)->size)
typedef struct _sbt{
	int val, size;
	struct _sbt *ch[2];
}SBTNode, *SBT;
SBTNode stack[Max_N];
int sz = 0;
void rotate(SBT *x, int d){
	SBT k = (*x)->ch[!d];
	(*x)->ch[!d] = k->ch[d];
	k->ch[d] = *x;
	k->size = (*x)->size;
	(*x)->size = size((*x)->ch[0]) + size((*x)->ch[1]) + 1;
	*x = k;
}
void Maintain(SBT *x, int d){
	if ((*x)->ch[d] == NULL) return;
	if (size((*x)->ch[d]->ch[d]) > size((*x)->ch[!d])) rotate(x, !d);
	else if (size((*x)->ch[d]->ch[!d]) > size((*x)->ch[!d])){
		rotate(&((*x)->ch[d]), d), rotate(x, !d);
	} else {
		return;
	}
	Maintain(&((*x)->ch[0]), 0);
	Maintain(&((*x)->ch[1]), 1);
	Maintain(x, 0);
	Maintain(x, 1);
}
void insert(SBT *x, int val){
	int d = 0;
	if (*x == NULL){
		*x = &stack[sz++];
		(*x)->val = val, (*x)->size = 1;
		(*x)->ch[0] = (*x)->ch[1] = NULL;
	} else {
		(*x)->size++;
		d = val > (*x)->val;
		insert(&((*x)->ch[d]), val);
		Maintain(x, val > (*x)->val);
	}
}
void _remove(SBT *x, int val){
	int d = 0;
	SBT ret = NULL;
	if ((*x) == NULL) return;
	(*x)->size--;
	if ((*x)->val == val){
		if ((*x)->ch[0] == NULL || (*x)->ch[1] == NULL){
			(*x) = ((*x)->ch[0] != NULL ? (*x)->ch[0] : (*x)->ch[1]);
		} else {
			ret = (*x)->ch[1];
			while (ret->ch[0] != NULL) ret = ret->ch[0];
			(*x)->val = ret->val;
			_remove(&((*x)->ch[1]), ret->val);
		}
	} else {
		d = val > (*x)->val;
		_remove(&((*x)->ch[d]), val);
	}
}
SBT find_kth(SBT x, int k){
	int t = 0;
	for (;;){
		t = size(x->ch[0]);
		if (k == t + 1) break;
		else if (k < t + 1) x = x->ch[0];
		else k -= t + 1, x = x->ch[1];
	}
	return x;
}
int find_rank(SBT x, int val, int cur){
	int t = 0;
	for (;;){
		t = size(x->ch[0]);
		if (x->val == val) break;
		else if (val < x->val) x = x->ch[0];
		else cur += t + 1, x = x->ch[1];
	}
	return cur + t + 1;
}
int pre(SBT x, int val){
	int ret = -1;
	for (; x != NULL;){
		if (val <= x->val){
			x = x->ch[0];
		} else {
			ret = x->val;
			x = x->ch[1];
		}
	}
	return ret;
}
int suc(SBT x, int val){
	int ret = -1;
	for (; x != NULL;){
		if (val >= x->val){
			x = x->ch[1];
		} else {
			ret = x->val;
			x = x->ch[0];
		}
	}
	return ret;
}
void travle(SBT x){
	if (x != NULL){
		travle(x->ch[0]);
		printf("%d ", x->val);
		travle(x->ch[1]);
	}
}
int main(){
	return 0;
}