九度oj 1184 二叉树遍历

原题链接：http://ac.jobdu.com/problem.php?pid=1184

简单的二叉树重建，遍历.

如下：

 #include<cstdio>
 #include<cstdlib>
 #include<cstring>
 #include<vector>
 struct node{
     char key;
     node *ch[];
     node(char d) : key(d) { ch[] = ch[] = NULL; }
 }*root = NULL;
 int n = ;
 static int k = -;
 char buf[];
 void built(node *&p){
     k++;
     if (k > n) return;
     if (buf[k] != '#'){
         p = new node(buf[k]);
         built(p->ch[]);
         built(p->ch[]);
     }
 }
 void travle(node *x){
     if (x != NULL){
         travle(x->ch[]);
         printf("%c ", x->key);
         travle(x->ch[]);
     }
 }
 void _free(node *x){
     if (x != NULL){
         _free(x->ch[]);
         _free(x->ch[]);
         delete x;
     }
 }
 int main(){
 #ifdef LOCAL
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w+", stdout);
 #endif
     while (~scanf("%s", buf)){
         k = -, root = NULL, n = strlen(buf);
         built(root);
         travle(root);
         _free(root);
         printf("\n");
     }
     return ;
 }