1020 Tree Traversals （25 分）（二叉树的遍历）

给出一个棵二叉树的后序遍历和中序遍历，求二叉树的层序遍历

#include<bits/stdc++.h>

using namespace std;
const int N=50;
int in[N];
int post[N];

typedef struct node;
typedef node *tree;
struct node
{
    int data;
    tree L;
    tree R;
};
void print(tree &bt,int l1,int r1,int l2,int r2)
{
    if(l1>r1||l2>r2) return;
    int mid=l2;
    while(in[mid]!=post[r1]) mid++;
    bt=new node;
    bt->data=post[r1];
    bt->L=NULL;
    bt->R=NULL;
    print(bt->L,l1,l1+mid-l2-1,l2,mid-1);
    print(bt->R,l1+mid-l2,r1-1,mid+1,r2);
}
vector<int>p;
void s(tree bt)
{
    queue<tree>Q;
    Q.push(bt);
    while(!Q.empty()){
        tree u=Q.front();
        Q.pop();
        p.push_back(u->data);
        if(u->L) Q.push(u->L);
        if(u->R) Q.push(u->R);
    }
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++) scanf("%d",&post[i]);
    for(int i=0;i<n;i++) scanf("%d",&in[i]);
    tree bt;
    print(bt,0,n-1,0,n-1);
    s(bt);
    for(int i=0;i<p.size();i++){
        if(i) printf(" ");
        printf("%d",p[i]);
    }
    printf("
");
    return 0;
}