1099

1099. Build A Binary Search Tree (30)

时间限制

100 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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.

  Given the structure of a binary tree and a sequence of distinct integer keys, there is only one way to fill these keys into the tree so that the resulting tree satisfies the definition of a BST. You are supposed to output the level order traversal sequence of that tree. The sample is illustrated by Figure 1 and 2.

  

  Input Specification:

  Each input file contains one test case. For each case, the first line gives a positive integer N (<=100) which is the total number of nodes in the tree. The next N lines each contains the left and the right children of a node in the format "left_index right_index", provided that the nodes are numbered from 0 to N-1, and 0 is always the root. If one child is missing, then -1 will represent the NULL child pointer. Finally N distinct integer keys are given in the last line.

  Output Specification:

  For each test case, print in one line the level order traversal sequence of that tree. All the numbers must be separated by a space, with no extra space at the end of the line.

  Sample Input:

  9
  1 6
  2 3
  -1 -1
  -1 4
  5 -1
  -1 -1
  7 -1
  -1 8
  -1 -1
  73 45 11 58 82 25 67 38 42
  

  Sample Output:

  58 25 82 11 38 67 45 73 42

• 
  

• #include <iostream>
  #include <cstdio>
  #include <algorithm>
  #include <queue>
  using namespace std;
  const int N = 100;
  struct Node
  {
      int left, right;
      int value;
  };
  Node node[N];
  int nums[N];
  int index = 0;
  void InOrder(int root)
  {
      if (node[root].left != -1)
          InOrder(node[root].left);
      node[root].value = nums[index++];
      if (node[root].right != -1)
          InOrder(node[root].right);
  }
  int main(void)
  {
      int n;
      scanf("%d", &n);
      for (int i = 0; i <n; ++i)
      {
          scanf("%d%d", &node[i].left, &node[i].right);
      }
      for (int i = 0; i < n; ++i)
      {
          scanf("%d", &nums[i]);
      }
      sort(nums, nums+n);
      InOrder(0);
      queue<int> que;
      que.push(0);
      // BFS
      index = 0;
      while (!que.empty())
      {
          int top = que.front();
          que.pop();
          nums[index++] = node[top].value;
          if (node[top].left != -1)
              que.push(node[top].left);
          if (node[top].right != -1)
              que.push(node[top].right);
      }
      // print result
      printf("%d", nums[0]);
      for (int i = 1; i < n; ++i)
          printf(" %d", nums[i]);
      printf("\n");
      return 0;
  }