1043 Is It a Binary Search Tree (25)
A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties:
- The left subtree of a node contains only nodes with keys less than the node's key.
- The right subtree of a node contains only nodes with keys greater than or equal to the node's key.
- Both the left and right subtrees must also be binary search trees.
If we swap the left and right subtrees of every node, then the resulting tree is called the Mirror Image of a BST.
Now given a sequence of integer keys, you are supposed to tell if it is the preorder traversal sequence of a BST or the mirror image of a BST.
Input Specification:
Each input file contains one test case. For each case, the first line contains a positive integer N (<=1000). Then N integer keys are given in the next line. All the numbers in a line are separated by a space.
Output Specification:
For each test case, first print in a line "YES" if the sequence is the preorder traversal sequence of a BST or the mirror image of a BST, or "NO" if not. Then if the answer is "YES", print in the next line the postorder traversal sequence of that tree. All the numbers in a line must be separated by a space, and there must be no extra space at the end of the line.
Sample Input 1:
7
8 6 5 7 10 8 11
Sample Output 1:
YES
5 7 6 8 11 10 8
Sample Input 2:
7
8 10 11 8 6 7 5
Sample Output 2:
YES
11 8 10 7 5 6 8
Sample Input 3:
7
8 6 8 5 10 9 11
Sample Output 3:
NO
#include<cstdio> #include<vector> using namespace std; struct Node{ int data; Node* left, *right; }; void insert(Node* &root,int data){ if(root == NULL){ root = new Node; root -> data = data; root -> left = root -> right = NULL; return; } if(data < root -> data) insert(root -> left,data); else insert(root -> right,data); } void preOrder(Node* root,vector<int>& vi){ //Node* &root 该&不能缺少 if(root == NULL) return; vi.push_back(root -> data); preOrder(root -> left,vi); preOrder(root -> right,vi); } void preOrderMirror(Node* root, vector<int> &vi){ if(root == NULL) return; vi.push_back(root -> data); preOrderMirror(root -> right,vi); preOrderMirror(root -> left,vi); } void postOrder(Node* root,vector<int> &vi){ if(root == NULL) return; postOrder(root -> left,vi); postOrder(root -> right,vi); vi.push_back(root -> data); } void postOrderMirror(Node* root,vector<int> &vi){ if(root == NULL) return; postOrderMirror(root ->right,vi); postOrderMirror(root -> left,vi); vi.push_back(root -> data); } vector<int> original,pre,preM,post,postM; int main(){ Node *root = NULL; int n,data; scanf("%d",&n); for(int i = 0; i < n; i++){ scanf("%d",&data); original.push_back(data); insert(root,data); } preOrder(root,pre); preOrderMirror(root,preM); postOrder(root,post); postOrderMirror(root,postM); if(original == pre){ printf("YES\n"); for(int i = 0; i < post.size(); i++){ printf("%d",post[i]); if(i < post.size() - 1) printf(" "); } }else if(original == preM){ printf("YES\n"); for(int i = 0; i < postM.size(); i++){ printf("%d",postM[i]); if(i < postM.size() - 1) printf(" "); } }else{ printf("NO"); } return 0; }
【推荐】国内首个AI IDE,深度理解中文开发场景,立即下载体验Trae
【推荐】编程新体验,更懂你的AI,立即体验豆包MarsCode编程助手
【推荐】抖音旗下AI助手豆包,你的智能百科全书,全免费不限次数
【推荐】轻量又高性能的 SSH 工具 IShell:AI 加持,快人一步
· 基于Microsoft.Extensions.AI核心库实现RAG应用
· Linux系列:如何用heaptrack跟踪.NET程序的非托管内存泄露
· 开发者必知的日志记录最佳实践
· SQL Server 2025 AI相关能力初探
· Linux系列:如何用 C#调用 C方法造成内存泄露
· 震惊!C++程序真的从main开始吗?99%的程序员都答错了
· 别再用vector<bool>了!Google高级工程师:这可能是STL最大的设计失误
· 单元测试从入门到精通
· 【硬核科普】Trae如何「偷看」你的代码?零基础破解AI编程运行原理
· 上周热点回顾(3.3-3.9)