H1002. 【模板】字典树 2

https://hydro.ac/record/615807f297ec9cde15d819a2

Hydro/H1002/H1002.cpp

@@ -2,54 +2,37 @@
 
 using namespace std;
 
-int n, a[1000005], ans;
+int n, a[1000005], trie[10000005][2], p = 1, 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);
+void insert(int u, int x, int b) {
+    if (!x) return;
+    if (!trie[u][(x >> b) & 1]) trie[u][(x >> b) & 1] = ++p;
+    insert(trie[u][(x >> b) & 1], x - (((x >> b) & 1) << b), b - 1);
 }
 
-int search(node* root, int x) {
-    int res = 0;
-    node* p = root;
+int search(int u, int x) {
+    int res = 0, t = u;
     for (int i = 30; i >= 0; i--) {
-        if (p == nullptr) break;
-        if (p->next[!((x >> i) & 1)] != nullptr) {
+        if (!t) break;
+        if (trie[t][!((x >> i) & 1)]) {
             res += 1 << i;
-            p = p->next[!((x >> i) & 1)];
+            t = trie[t][!((x >> i) & 1)];
         } else {
-            p = p->next[(x >> i) & 1];
+            t = trie[t][(x >> i) & 1];
         }
     }
     return res;
 }
 
 int main() {
-    node* root = new node();
     scanf("%d", &n);
     for (int i = 0; i < n; i++) {
         scanf("%d", a + i);
-        insert(root, a[i], 30);
+        insert(1, a[i], 30);
     }
     for (int i = 0; i < n; i++) {
-        ans = max(ans, search(root, a[i]));
+        ans = max(ans, search(1, a[i]));
     }
     printf("%d\n", ans);
-    delete root;
     return 0;
 }