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天梯赛练习——树的遍历 (25分)

程序员文章站 2022-06-07 21:47:02
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题目:

天梯赛练习——树的遍历 (25分)

代码:

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;

const int MAXN = 35;
int n;
int mid[MAXN],last[MAXN],ans[MAXN];

typedef struct node* TE;
struct node
{
    int val;
    TE l=NULL,r=NULL;
};

TE BuildTree(int root,int st,int ed)
{
    if(st > ed) return NULL;
    int index = st;
    while(mid[index] != last[root]) index++;
    TE tree = new node();
    tree->val = last[root];
    tree->l = BuildTree(root-1-ed+index,st,index-1);  //这里第一个参数不是index-1(牢记)
    tree->r = BuildTree(root-1,index+1,ed);
    return tree;
}

int main()
{
    scanf("%d",&n);
    queue<TE> q;
    for(int i=1;i<=n;++i)
        scanf("%d",&last[i]);
    for(int i=1;i<=n;++i)
        scanf("%d",&mid[i]);
    TE tre = NULL;
    tre = BuildTree(n,1,n);
    q.push(tre);
    int ind=0;
    while(!q.empty())
    {
        TE now = q.front();
        q.pop();
        ans[++ind] = now->val;
        if(now->l != NULL)
            q.push(now->l);
        if(now->r != NULL)
            q.push(now->r);
    }
    for(int i=1;i<=ind;++i)
        if(i == ind)
            printf("%d\n",ans[i]);
        else
            printf("%d ",ans[i]);
    return 0;
}

相关标签: # 天梯赛