输入广义表建立二叉树（层序输出）

#include <bits/stdc++.h>
using namespace std;
struct node{
	char ch;
	node *lc,*rc;
}; 
char s[100];
int flag=0;
int n;
int i=0;
node * build_tree()
{
	if(i>=n)
	return NULL;
	node *p = new node;
	p->lc = NULL; p->rc = NULL; p->ch = '0';//初始化 
  for(;i<n;i++)
	{
	if(flag)
	{
		flag = 0;
		p->rc = build_tree();
		
	}else if(s[i]=='(')
	{
		++i;
		p->lc = build_tree(); 
		
	}else if(s[i]==',')
	{	
	    flag = 1; 
	    if(p->ch=='0')return NULL;
	    else return p;
	}else if(s[i]>='A'&&s[i]<='Z')
	{
		p->ch = s[i];
	}else if(s[i]==')')
	{
		return p;
	}
	
	}
	return p;
}
void print(node *p)
{
	queue<node*>q;
	while(!q.empty())q.pop();
	q.push(p);
	while(!q.empty())
	{
		node *t = q.front();
		q.pop();
		printf("%c ",t->ch);
		if(t->lc)q.push(t->lc); 
		if(t->rc)q.push(t->rc);
	} 
}

int main()
{
 	scanf("%s",s);
 	n = strlen(s);
 	node *root = build_tree();
	print(root);
	
	return 0;
}
//A(B(E(K,L),F),C(D(,H)))