From 744059e7b1e963753f636e78f6bfb1cd29a110ba Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Thu, 11 Jan 2024 15:19:44 +0100
Subject: [PATCH] =?UTF-8?q?cpp:=20add=20=E2=80=9C1026.=20Maximum=20Differe?=
 =?UTF-8?q?nce=20Between=20Node=20and=20Ancestor=E2=80=9D?=
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Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 ...m-difference-between-node-and-ancestor.cpp | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 cpp/maximum-difference-between-node-and-ancestor.cpp

diff --git a/cpp/maximum-difference-between-node-and-ancestor.cpp b/cpp/maximum-difference-between-node-and-ancestor.cpp
new file mode 100644
index 0000000..6c12812
--- /dev/null
+++ b/cpp/maximum-difference-between-node-and-ancestor.cpp
@@ -0,0 +1,39 @@
+#include <limits>
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
+ * right(right) {}
+ * };
+ */
+class Solution {
+    int maxAncestorDiff(TreeNode *node, int lower, int upper) const {
+        if (node == nullptr) {
+            return 0;
+        }
+
+        auto diff =
+            std::max(std::abs(node->val - lower), std::abs(node->val - upper));
+        auto [next_lower, next_upper] = std::make_tuple(
+            std::min(lower, node->val), std::max(upper, node->val));
+
+        diff =
+            std::max(diff, maxAncestorDiff(node->left, next_lower, next_upper));
+        diff = std::max(diff,
+                        maxAncestorDiff(node->right, next_lower, next_upper));
+
+        return diff;
+    }
+
+  public:
+    int maxAncestorDiff(TreeNode *root) {
+        auto default_bound = root != nullptr ? root->val : 0;
+        return maxAncestorDiff(root, default_bound, default_bound);
+    }
+};