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| class Solution {
private static class Result {
private int maxDiff;
}
public int maxAncestorDiff(TreeNode root) {
Result result = new Result();
dfs(result, root, null, null);
return result.maxDiff;
}
private void dfs(Result result, TreeNode node, Integer min, Integer max) {
if (node == null) {
return;
}
if (min != null) {
result.maxDiff = Math.max(result.maxDiff, Math.abs(node.val - min));
}
if (max != null) {
result.maxDiff = Math.max(result.maxDiff, Math.abs(max - node.val));
}
min = min == null ? node.val : Math.min(min, node.val);
max = max == null ? node.val : Math.max(max, node.val);
dfs(result, node.left, min, max);
dfs(result, node.right, min, max);
}
}
|