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100. Same Tree
Given two binary trees, write a function to check if they are the same or not.
Two binary trees are considered the same if they are structurally identical and the nodes have the same value.
Example 1:
Input: 1 1
/ \ / \
2 3 2 3
[1,2,3], [1,2,3]
Output: true
Example 2:
Input: 1 1
/ \
2 2
[1,2], [1,null,2]
Output: false
Example 3:
Input: 1 1
/ \ / \
2 1 1 2
[1,2,1], [1,1,2]
Output: false
思考题
尝试一下迭代的解决方案。
Given two binary trees, write a function to check if they are the same or not.
Two binary trees are considered the same if they are structurally identical and the nodes have the same value.
Example 1:
Input: 1 1
/ \ / \
2 3 2 3
[1,2,3], [1,2,3]
Output: true
Example 2:
Input: 1 1
/ \
2 2
[1,2], [1,null,2]
Output: false
Example 3:
Input: 1 1
/ \ / \
2 1 1 2
[1,2,1], [1,1,2]
Output: false
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/**
* Runtime: 0 ms, faster than 100.00% of Java online submissions for Same Tree.
* Memory Usage: 36.4 MB, less than 5.75% of Java online submissions for Same Tree.
*/
public boolean isSameTree(TreeNode p, TreeNode q) {
if (Objects.isNull(p) && Objects.isNull(q)) {
return true;
}
if (Objects.isNull(p) || Objects.isNull(q)) {
return false;
}
if (p.val != q.val) {
return false;
}
boolean left = isSameTree(p.left, q.left);
if (!left) {
return false;
}
return isSameTree(p.right, q.right);
}
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public boolean isSameTree(TreeNode p, TreeNode q) {
if (p == null && q == null) {
return true;
}
if ((p == null && q != null)
|| (p != null && q == null)
|| p.val != q.val) {
return false;
}
return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}