Leetcode
2020.04.30 11:47

# 993. Cousins in Binary Tree

조회 수 256 추천 수 0 댓글 0
?

#### 단축키

Prev이전 문서

Next다음 문서

크게 작게 위로 아래로 댓글로 가기 인쇄 첨부
?

#### 단축키

Prev이전 문서

Next다음 문서

크게 작게 위로 아래로 댓글로 가기 인쇄 첨부

In a binary tree, the root node is at depth `0`, and children of each depth `k` node are at depth `k+1`.

Two nodes of a binary tree are cousins if they have the same depth, but have different parents.

We are given the `root` of a binary tree with unique values, and the values `x` and `y` of two different nodes in the tree.

Return `true` if and only if the nodes corresponding to the values `x` and `y` are cousins.

Example 1:

```Input: root = [1,2,3,4], x = 4, y = 3
Output: false
```

Example 2:

```Input: root = [1,2,3,null,4,null,5], x = 5, y = 4
Output: true
```

Example 3:

```Input: root = [1,2,3,null,4], x = 2, y = 3
Output: false```

Note:

1. The number of nodes in the tree will be between `2` and `100`.
2. Each node has a unique integer value from `1` to `100`.

```/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode() {}
*     TreeNode(int val) { this.val = val; }
*     TreeNode(int val, TreeNode left, TreeNode right) {
*         this.val = val;
*         this.left = left;
*         this.right = right;
*     }
* }
*/

class Solution {
public boolean isCousins(TreeNode root, int x, int y) {
if(root == null){
return false;
}

int depth = 0;
int depth1 = 0;
int depth2 = 0;
TreeNode parent1 = null;
TreeNode parent2 = null;

Map<TreeNode, TreeNode> hmap = new HashMap<>();

queue.offer(root);
hmap.put(root, null);

while(queue.size() > 0){
depth++;
int size = queue.size();

for(int i=0; i<size; i++){
TreeNode node = queue.poll();

if(node.left != null){
queue.offer(node.left);
hmap.put(node.left, node);
}
if(node.right != null){
queue.offer(node.right);
hmap.put(node.right, node);
}

if(node.val == x){
depth1 = depth;
parent1 = hmap.get(node);
}
if(node.val == y){
depth2 = depth;
parent2 = hmap.get(node);
}
}
}

return parent1 != parent2 && depth1 == depth2;
}
}```

```/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode() {}
*     TreeNode(int val) { this.val = val; }
*     TreeNode(int val, TreeNode left, TreeNode right) {
*         this.val = val;
*         this.left = left;
*         this.right = right;
*     }
* }
*/
class Solution {
Map<Integer, TreeNode> hmap;

public boolean isCousins(TreeNode root, int x, int y) {
hmap = new HashMap<>();

int depth1 = findDepth(root, x, 0);
int depth2 = findDepth(root, y, 0);

return hmap.get(x) != hmap.get(y) && depth1 == depth2;
}

public int findDepth(TreeNode node, int val, int depth){
if(node == null){
return 0;
}

if(node.left != null && node.left.val == val){
hmap.put(val, node);
}
if(node.right != null && node.right.val == val){
hmap.put(val, node);
}

if(node.val != val){
int left = findDepth(node.left, val, depth + 1);
int right = findDepth(node.right, val, depth + 1);

return Math.max(left, right);
}

return depth + 1;
}
}```

[문제] https://leetcode.com/problems/cousins-in-binary-tree/

?

 제목+내용제목내용댓글이름닉네임아이디태그
List of Articles
번호 분류 제목 글쓴이 날짜 조회 수
77 Leetcode [todo] 687. Longest Univalue Path 2020.05.01 238
76 Programmers team game 2020.04.30 0
75 Programmers hashmap 2020.04.30 0
74 Programmers fib 2020.04.30 0
73 Leetcode 997. Find the Town Judge 2020.05.02 761
72 Leetcode 994. Rotting Oranges 2020.04.14 212
» Leetcode 993. Cousins in Binary Tree 2020.04.30 256
70 Leetcode 973. K Closest Points to Origin 2020.04.15 210
69 Leetcode 946. Validate Stack Sequences 2020.04.08 194
68 Leetcode 937. Reorder Data in Log Files 2020.04.25 200
67 Leetcode 897. Increasing Order Search Tree 2020.05.04 725
66 Leetcode 876. Middle of the Linked List 2020.05.04 711
65 Leetcode 872. Leaf-Similar Trees 2020.05.04 719
64 Leetcode 852. Peak Index in a Mountain Array 2020.04.28 203
63 Leetcode 844. Backspace String Compare 2020.05.05 824
62 Leetcode 783. Minimum Distance Between BST Nodes 2020.05.01 768
61 Leetcode 763. Partition Labels 2020.04.17 256
60 Leetcode 75. Sort Colors 2020.04.14 184
59 Leetcode 731. My Calendar II 2020.04.15 194
58 Leetcode 729. My Calendar I 2020.04.15 187
Board Pagination Prev 1 2 3 4 Next
/ 4