sicily 1935. 二叉树重建

#include <iostream>            //根据先序遍历序列和中序遍历序列建立二叉树,并按层遍历
#include <string>
using namespace std;
string str1,str2;
int n;
struct Node 
{
    char ch;
    Node *left,*right;
}node[5000];
Node* built(int s1,int t1,int s2,int t2)    //根据先序遍历序列和中序遍历序列建二叉树
{
    int m=n++;        //声明为局部变量
    node[m].ch=str1[s1];
    int mid=str2.find(str1[s1]);    //str1[s1]为根结点字符
    if(s2<mid)
        node[m].left=built(s1+1,s1+mid-s2,s2,mid-1);    //递归构造左子树,左子树结点总数是mid-s2    

    if(t2>mid)
        node[m].right=built(s1+mid-s2+1,t1,mid+1,t2);    //递归构造右子树,右子树结点总数是t2-mid

    return &node[m];    //返回根结点指针
}
void bfs(Node *root)    //按层遍历
{
    Node *col[1000],*temp;
    int front=0,rear=0;
    col[rear++]=root;
    while(front<rear)
    {
        temp=col[front++];
        cout<<temp->ch;
        if(temp->left!=NULL)
        {
            col[rear++]=temp->left;
            temp->left=NULL;    //遍历时顺便对整棵树进行初始化
        }
        if(temp->right!=NULL)
        {
            col[rear++]=temp->right;
            temp->right=NULL;
        }
    }
    cout<<endl;
}
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        cin>>str1>>str2;
        n=0;
        Node *root=built(0,str1.size()-1,0,str2.size()-1);
        bfs(root);
    }
    return 0;
}