1+ #include < vector>
2+ #include < algorithm>
3+ #include < iostream>
4+ #include < unordered_map>
5+ using namespace std ;
6+ /* *
7+ * Definition for a binary tree node.
8+ */
9+ struct TreeNode {
10+ int val;
11+ TreeNode *left;
12+ TreeNode *right;
13+ TreeNode () : val(0 ), left(nullptr ), right(nullptr ) {}
14+ TreeNode (int x) : val(x), left(nullptr ), right(nullptr ) {}
15+ TreeNode (int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
16+ };
17+ 18+ class Solution {
19+ public:
20+ bool isCousins (TreeNode* root, int x, int y) {
21+ unordered_map<int , int > depths; /* map: value -> depth */
22+ unordered_map<int , int > parents; /* map: value -> parent value */
23+ dfs (root, 0 , depths, parents);
24+ if (depths[x] == depths[y] && parents[x] != parents[y])
25+ return true ;
26+ return false ;
27+ }
28+ void dfs (TreeNode* root, int depth, unordered_map<int , int >& depths, unordered_map<int , int >& parents)
29+ {
30+ if (root == nullptr ) return ;
31+ depths[root->val ] = depth;
32+ if (root->left != nullptr )
33+ {
34+ parents[root->left ->val ] = root->val ;
35+ dfs (root->left , depth + 1 , depths, parents);
36+ }
37+ if (root->right != nullptr )
38+ {
39+ parents[root->right ->val ] = root->val ;
40+ dfs (root->right , depth + 1 , depths, parents);
41+ }
42+ return ;
43+ }
44+ };
45+ 46+ // Test
47+ int main ()
48+ {
49+ Solution sol;
50+ TreeNode* root = new TreeNode (1 );
51+ root->left = new TreeNode (2 );
52+ root->right = new TreeNode (3 );
53+ root->left ->right = new TreeNode (4 );
54+ root->right ->right = new TreeNode (5 );
55+ auto res = sol.isCousins (root, 2 , 3 );
56+ cout << (res ? " True" " False"
57+ 58+ return 0 ;
59+ }
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