From d08421fad2eb6b228e6ee8dd28a79c660146724c Mon Sep 17 00:00:00 2001
From: Ren Baoshuo <i@baoshuo.ren>
Date: Sun, 12 Sep 2021 15:50:07 +0800
Subject: [PATCH] =?UTF-8?q?143.=20=E6=9C=80=E5=A4=A7=E5=BC=82=E6=88=96?=
 =?UTF-8?q?=E5=AF=B9?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

https://www.acwing.com/problem/content/submission/code_detail/7682567/
---
 AcWing/143/143.cpp | 55 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 AcWing/143/143.cpp

diff --git a/AcWing/143/143.cpp b/AcWing/143/143.cpp
new file mode 100644
index 00000000..c647a2b9
--- /dev/null
+++ b/AcWing/143/143.cpp
@@ -0,0 +1,55 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, a[100005], ans;
+
+struct node {
+    int val;
+    node* next[2];
+
+    ~node() {
+        for (auto i : next) {
+            delete i;
+        }
+    }
+};
+
+void insert(node* root, int x, int b) {
+    if (!x) {
+        root->val++;
+        return;
+    }
+    if (root->next[(x >> b) & 1] == nullptr) root->next[(x >> b) & 1] = new node();
+    insert(root->next[(x >> b) & 1], x - (((x >> b) & 1) << b), b - 1);
+}
+
+int search(node* root, int x) {
+    int res = 0;
+    node* p = root;
+    for (int i = 30; i >= 0; i--) {
+        if (p == nullptr) break;
+        if (p->next[!((x >> i) & 1)] != nullptr) {
+            res += 1 << i;
+            p = p->next[!((x >> i) & 1)];
+        } else {
+            p = p->next[(x >> i) & 1];
+        }
+    }
+    return res;
+}
+
+int main() {
+    node* root = new node();
+    cin >> n;
+    for (int i = 0; i < n; i++) {
+        cin >> a[i];
+        insert(root, a[i], 30);
+    }
+    for (int i = 0; i < n; i++) {
+        ans = max(ans, search(root, a[i]));
+    }
+    cout << ans << endl;
+    delete root;
+    return 0;
+}