数据结构实验之求二叉树后序遍历和层次遍历

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
typedef struct tree
{
    char data;
    struct tree *l,*r;
}BinTree;
BinTree *creat(char *pre, char *in, int len)
{
    int k;
    if(len<=0)
        return NULL;
    BinTree *head;
    head=(BinTree*)malloc(sizeof(BinTree));
    head->data=*pre;
    char *p;
    for(p=in;p!=NULL;p++)
        if(*p==*pre)
            break;// 在中序遍历的序列中得到与先序相同的节点
    k=p-in;
    head->l=creat(pre+1,in,k);//递归得到左子树
    head->r=creat(pre+k+1,p+1,len-k-1);//得到右子树
    return head;
}
void postorder(BinTree *t)
{
    if(t)
    {
        postorder(t->l);
        postorder(t->r);
        printf("%c",t->data);
    }
}
void lorder(BinTree *t)
{
    int front=0,rear=1;
    BinTree *q[100];
    q[0]=t;
    while(front<rear)
    {
        if(q[front])
        {
            printf("%c",q[front]->data);
            q[rear++]=q[front]->l;
            q[rear++]=q[front]->r;
            front++;
        }
        else
            front++;
    }
}
int main()
{
    int t,len;
    char pre[101],in[101];
    BinTree *root;
    root = (BinTree *)malloc(sizeof(BinTree));
    scanf("%d",&t);
    getchar();
    while(t--)
    {
        scanf("%s %s",pre,in);
        len = strlen(pre);
        root = creat(pre,in,len);
        postorder(root);
        printf("\n");
        lorder(root);
        printf("\n");
    }
    return 0;
}