2017 年

typedef struct node{
	char data[10];
	struct node *left,*right;
}BTree;
 
void in_traverse(BTree* node,string s){
	if(node!=NULL){
		in_traverse(node->left,s);
		if(node->left!=NULL ||node->right!=NULL){
			s+="("+node->data+")";
		}else{
			s+=node->data;
		}
		in_traverse(node->right,s);
	}
}
 
string to_expression(BTree* node){
	string s="";
	in_traverse(node,s);
	return s;
}