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java: add «2415. Reverse Odd Levels of Binary Tree»

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URL:	https://leetcode.com/problems/reverse-odd-levels-of-binary-tree/
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Matej Focko 2024-12-20 22:16:12 +01:00
parent f0aa77436b
commit f6084d4af5
Signed by: mfocko
SSH key fingerprint: SHA256:icm0fIOSJUpy5+1x23sfr+hLtF9UhY8VpMC7H4WFJP8
1 changed files with 39 additions and 0 deletions
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java/reverse-odd-levels-of-binary-tree.java Normal file
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class Solution {
private void traverse(ArrayList<ArrayList<TreeNode>> nodes, int level, TreeNode node) {
if (node == null) {
return;
}
if (level % 2 == 1) {
var idx = level >> 1;
while (nodes.size() <= idx) {
nodes.addLast(new ArrayList<TreeNode>());
}
nodes.get(idx).addLast(node);
}
traverse(nodes, level + 1, node.left);
traverse(nodes, level + 1, node.right);
}
private void reverse(ArrayList<TreeNode> level) {
int i, j;
for (i = 0, j = level.size() - 1; i < j; ++i, --j) {
var tmp = level.get(i).val;
level.get(i).val = level.get(j).val;
level.get(j).val = tmp;
}
}
public TreeNode reverseOddLevels(TreeNode root) {
var nodes = new ArrayList<ArrayList<TreeNode>>();
traverse(nodes, 0, root);
for (var level : nodes) {
reverse(level);
}
return root;
}
}