思路
记录节点的深度和父节点
代码
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int x_depth,y_depth,x_parent,y_parent;
bool isCousins(TreeNode* root, int x, int y) {
dfs(root->left,1,x,y,root->val);
dfs(root->right,1,x,y,root->val);
return (x_parent!=y_parent) && (x_depth == y_depth);
}
void dfs(TreeNode* node ,int depth , int x, int y , int parent){
if(node == nullptr) return ;
if(node->val == x){
x_parent = parent;
x_depth = depth;
}
else if(node->val == y){
y_parent = parent;
y_depth = depth;
}
else {
dfs(node->left,depth+1,x,y,node->val);
dfs(node->right,depth+1,x,y,node->val);
}
}
};