Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, you are supposed to output the level order traversal sequence of the corresponding binary tree.
Each input file contains one test case. For each case, the first line gives a positive integer N (≤), the total number of nodes in the binary tree. The second line gives the postorder sequence and the third line gives the inorder sequence. All the numbers in a line are separated by a space.
For each test case, print in one line the level order traversal sequence of the corresponding binary tree. All the numbers in a line must be separated by exactly one space, and there must be no extra space at the end of the line.
7
2 3 1 5 7 6 4
1 2 3 4 5 6 7
4 1 6 3 5 7 2
已知后序遍历和中序遍历输出层序遍历
1 #include <iostream> 2 #include <queue> 3 using namespace std; 4 int *pos, *ord;//存放后序和中序遍历数据 5 struct Node 6 { 7 int val; 8 Node *l, *r; 9 Node(int a = 0) :val(a), l(nullptr), r(nullptr) {} 10 }; 11 Node* createTree(int posL,int posR, int ordL, int ordR) 12 { 13 if (posL > posR) 14 return nullptr; 15 Node *root = new Node(); 16 root->val = pos[posR];//根节点值 17 int k; 18 for (k = ordL; k <= ordR; ++k) 19 { 20 if (ord[k] == pos[posR])//找到原树的根 21 break; 22 } 23 int numL = k - ordL;//左子树节点数量 24 //递归构造左子树 25 root->l = createTree(posL, posL + numL - 1, ordL, k - 1); 26 //递归构造右子树 27 root->r = createTree(posL + numL, posR - 1, k + 1, ordR);//取出根节点 28 return root; 29 } 30 void getResBFS(Node* root) 31 { 32 queue<Node*>q; 33 Node* p = nullptr; 34 q.push(root); 35 cout << root->val; 36 while (!q.empty()) 37 { 38 p = q.front(); 39 if (p != root) 40 cout << " " << p->val; 41 q.pop(); 42 if (p->l != nullptr) 43 q.push(p->l); 44 if (p->r != nullptr) 45 q.push(p->r); 46 } 47 cout << endl; 48 } 49 50 int main() 51 { 52 int N; 53 cin >> N; 54 pos = new int[N]; 55 ord = new int[N]; 56 for (int i = 0; i < N; ++i) 57 cin >> pos[i]; 58 for (int i = 0; i < N; ++i) 59 cin >> ord[i]; 60 Node* root = createTree(0, N - 1, 0, N - 1); 61 getResBFS(root); 62 return 0; 63 }
原文：https://www.cnblogs.com/zzw1024/p/11228888.html