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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. using ll = long long;
  5.  
  6. struct TreeNode{
  7. 	int val;
  8. 	TreeNode* left;
  9. 	TreeNode* right;
  10.  
  11. 	TreeNode(int val):val(val),left(nullptr),right(nullptr){};
  12. };
  13. int ans = 0;
  14. int dfs(TreeNode* root,int tar,int &dist){
  15. 	if(!root)return 0;
  16.  
  17. 	int ld,rd = -1;
  18.  
  19. 	int lh = dfs(root->left,tar,ld);
  20. 	int rh = dfs(root->left,tar,rd);
  21.  
  22. 	if(root->val  == tar){
  23. 		dist = 0;
  24. 		ans = max(ans,max(lh,rh));
  25. 	}else if(ld != -1){
  26. 		dist = ld+1;
  27. 		ans = max(ans,rh);
  28. 	}else if(rd !=  -1){
  29. 		dist = rd+1;
  30. 		ans = max(ans,lh);
  31. 	}
  32. 	return 1+max(lh,rh);
  33. }
  34. int burn(TreeNode* root,int tar){
  35. 	if(!root)return 0;
  36. 	ans = 0;
  37. 	int dist = -1;
  38. 	dfs(root,tar,dist);
  39. 	return ans;
  40. }
  41. TreeNode* buildTree(){
  42. 	int x; cin>>x;
  43. 	if(x == -1)return nullptr;;
  44.  
  45. 	TreeNode* root = new TreeNode(x);
  46. 	queue<TreeNode*>q;
  47. 	q.push(root);
  48.  
  49. 	while(!q.empty()){
  50. 		auto u = q.front();
  51. 		q.pop();
  52.  
  53. 		if(cin>>x && x!=-1){
  54. 			u->left = new TreeNode(x);
  55. 			q.push(u->left);
  56. 		}
  57.  
  58. 			if(cin>>x && x!=-1){
  59. 			u->right = new TreeNode(x);
  60. 			q.push(u->right);
  61. 		}
  62. 	}
  63. 	return root;
  64. }
  65.  
  66. int main() {
  67. TreeNode* root = buildTree();
  68. int val;cin>>val;
  69. cout<<burn(root,val);
  70.  
  71.  
  72. 	return 0;
  73. }
Success #stdin #stdout 0s 5316KB
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https://ideone.com/pqp6r8
language:
C++14 (gcc 8.3)
created:
1 hour ago
visibility:
public

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