题目：https://pintia.cn/problem-sets/994805342720868352/problems/994805367987355648
有了上一题的基础，这题很快就过了，也没啥可说的，一个注意点是押入队列的时候不要忘了判断一下是否存在

代码

  1. #include<cstdio>
  2. #include<iostream>
  3. #include<algorithm>
  4. #include<vector>
  5. #include<queue>
  6. using namespace std;
  8. const int maxn = 110;
  9. struct Node{
  10.     int data, lchild, rchild;
  11. }node[maxn];
  13. int n, index = 0;
  14. int number[maxn];
  15. void in_order(int root){
  16.     if(root == -1) return;
  17.     in_order(node[root].lchild);
  18.     node[root].data = number[index++];
  19.     in_order(node[root].rchild);
  20. }
  22. void BFS(int root){
  23.     queue<int> q;
  24.     q.push(root);
  25.     while(!q.empty()){
  26.         int top = q.front();
  27.         q.pop();
  28.         printf("%d",node[top]);
  29.         if(node[top].lchild != -1) q.push(node[top].lchild);
  30.         if(node[top].rchild != -1) q.push(node[top].rchild);
  31.         if(q.size() != 0) printf(" ");
  32.     }
  33. }
  35. int main(){
  36.     int  lchild, rchild;
  37.     scanf("%d",&n);
  38.     for(int i = 0; i < n; i++){
  39.         scanf("%d%d", &lchild, &rchild);
  40.         node[i].lchild = lchild;
  41.         node[i].rchild = rchild;
  42.     }
  43.     for(int i = 0; i < n; i++){
  44.         scanf("%d",&number[i]);
  45.     }
  46.     sort(number, number + n);
  47.     in_order(0);
  48.     BFS(0);
  49.     return 0;
  50. }