The following is from Max Howell @twitter:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can‘t invert a binary tree on a whiteboard so fuck off.
Now it‘s your turn to prove that YOU CAN invert a binary tree!
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (≤) which is the total number of nodes in the tree -- and hence the nodes are numbered from 0 to N−1. Then N lines follow, each corresponds to a node from 0 to N−1, and gives the indices of the left and right children of the node. If the child does not exist, a -
will be put at the position. Any pair of children are separated by a space.
Output Specification:
For each test case, print in the first line the level-order, and then in the second line the in-order traversal sequences of the inverted tree. There must be exactly one space between any adjacent numbers, and no extra space at the end of the line.
Sample Input:
8
1 -
- -
0 -
2 7
- -
- -
5 -
4 6
Sample Output:
3 7 2 6 4 0 5 1
6 5 7 4 3 2 0 1
这题是依次给出节点的左孩子右孩子,进行找出翻转二叉树的层序遍历和中序遍历。
我们可以使用中序遍历进行构建树,之后进行使用sort根据level进行从小到大,根据index进行从大到小。即可获得翻转二叉树的层序遍历。
最后打印
#include <iostream> #include <string> #include <vector> #include <algorithm> using namespace std; struct node { int index, id, left = -1, right = -1, level; }a[100]; int N; vector<node> v; bool cmp(node& n1, node& n2){ return n1.level == n2.level ? n1.index > n2.index: n1.level < n2.level; } void dfs(int root, int index, int level){ if(a[root].right != -1) dfs(a[root].right, index * 2 + 2, level + 1); v.push_back({index, root, 0, 0, level}); if(a[root].left != -1) dfs(a[root].left, index * 2 + 1, level + 1); } int main(){ cin >> N; string tmp_l, tmp_r; vector<bool> find_root(N); for(int i = 0; i < N; i++){ cin >> tmp_l >> tmp_r; a[i].id = i; if(tmp_l != "-") { a[i].left = stoi(tmp_l); find_root[stoi(tmp_l)] = true; } if(tmp_r != "-") { a[i].right = stoi(tmp_r); find_root[stoi(tmp_r)] = true; } } int root_index; for(int i = 0; i < N; i++) if(!find_root[i]) root_index = i; dfs(root_index, 0, 0); vector<node> v2(v); sort(v2.begin(), v2.end(), cmp); for(int i = 0; i < N; i++) if(i != N-1) cout << v2[i].id << " "; else cout << v2[i].id <<endl; for(int i = 0; i < N; i++) if(i != N-1) cout << v[i].id << " "; else cout << v[i].id <<endl; system("pause"); return 0; }
原文地址:https://www.cnblogs.com/littlepage/p/12234525.html