二叉树递归遍历 已知先序、中序求后序序列，已知中序、后序求先序序例

二叉树数据结构定义

typedef char TElemType;
typedef struct TreeNode
{
    struct TreeNode *lchild;
    struct TreeNode *rchild;
    TElemType data;
}TreeNode,*Tree;

二叉树递归遍历

void PreOrderTraverse(Tree &T)
{
    if (T) {
        printf("%c",T->data);
    }
    if (T->lchild) {
        PreOrderTraverse(T->lchild);
    }
    if (T->rchild) {
        PreOrderTraverse(T->rchild);
    }
}
void InOrderTraverse(Tree &T)
{
    if (T->lchild) {
        InOrderTraverse(T->lchild);
    }
    printf("%c",T->data);
    if (T->rchild) {
        InOrderTraverse(T->rchild);
    }
}
void PostOrderTraverse(Tree &T)
{
    if (T->lchild) {
        PostOrderTraverse(T->lchild);
    }
    if (T->rchild) {
        PostOrderTraverse(T->rchild);
    }
    printf("%c",T->data);
}

已知先序、中序求后序序列

#include 
typedef char TElemType;
typedef struct TreeNode
{
    struct TreeNode *lchild;
    struct TreeNode *rchild;
    TElemType data;
}TreeNode,*Tree;
Tree create(TElemType data);
Tree BuildBiTree(int s1,int e1,int s2,int e2);
void PostTraverse(Tree &T);
char pre[30],in[30];
int main()
{
    while (scanf("%s",pre)!=EOF) {
        scanf("%s",in);
        int l1=(int)strlen(pre);
        int l2=(int)strlen(in);
        Tree T=BuildBiTree(0, l1-1, 0, l2-1);
        PostTraverse(T);
        printf("\n");
    }
    return 0;
}
Tree create(TElemType data)
{
    Tree T=new TreeNode;
    T->lchild=T->rchild=NULL;
    T->data=data;
    return T;
}
Tree BuildBiTree(int s1,int e1,int s2,int e2)
{
    Tree T=create(pre[s1]);
    int rootposition=0;
    for (int i=s2; i<=e2; i++) {
        if (pre[s1]==in[i]) {
            rootposition=i;
            break;
        }
    }
    if (rootposition!=s2) {
        T->lchild=BuildBiTree(s1+1, s1+rootposition-s2, s2, rootposition-1);
    }
    if (rootposition!=e2) {
        T->rchild=BuildBiTree(s1+rootposition-s2+1, e1, rootposition+1, e2);
    }
    return T;
}
void PostTraverse(Tree &T)
{
    if (T->lchild) {
        PostTraverse(T->lchild);
    }
    if (T->rchild) {
        PostTraverse(T->rchild);
    }
    printf("%c",T->data);
}

已知中序、后序求先序序列

#include 
typedef char TElemType;
typedef struct TreeNode
{
    struct TreeNode *lchild;
    struct TreeNode *rchild;
    TElemType data;
}TreeNode,*Tree;
Tree create(TElemType data);
Tree BuildBiTree(int s1,int e1,int s2,int e2);
void PreOrderTraverse(Tree &T);
char in[30],post[30];
int main()
{
    while (scanf("%s",in)!=EOF) {
        scanf("%s",post);
        int l1=(int)strlen(in);
        int l2=(int)strlen(post);
        Tree T=BuildBiTree(0, l1-1, 0, l2-1);
        PreOrderTraverse(T);
        printf("\n");
    }
    return 0;
}
Tree create(TElemType data)
{
    Tree T=new TreeNode;
    T->lchild=T->rchild=NULL;
    T->data=data;
    return T;
}
Tree BuildBiTree(int s1,int e1,int s2,int e2)
{
    Tree T=create(post[e2]);
    int rootposition=0;
    for (int i=s1; i<=e1; i++) {
        if (post[e2]==in[i]) {
            rootposition=i;
            break;
        }
    }
    if (rootposition!=s1) {
        T->lchild=BuildBiTree(s1, rootposition-1, s2, s2+rootposition-s1-1);
    }
    if (rootposition!=e1) {
        T->rchild=BuildBiTree(rootposition+1, e1, s2+rootposition-s1, e2-1);
    }
    return T;
}
void PreOrderTraverse(Tree &T)
{
    if (T) {
        printf("%c",T->data);
    }
    if (T->lchild) {
        PreOrderTraverse(T->lchild);
    }
    if (T->rchild) {
        PreOrderTraverse(T->rchild);
    }
}