835. Trie字符串统计

https://www.acwing.com/problem/content/submission/code_detail/7680320/

AcWing/835/835.cpp

@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n;
+char op;
+string s;
+
+struct node {
+    int val;
+    node* next[30];
+
+    ~node() {
+        for (auto i : next) {
+            delete i;
+        }
+    }
+};
+
+void insert(node* root, string s) {
+    if (s.empty()) {
+        root->val++;
+        return;
+    }
+    if (root->next[s[0] - 'a'] == nullptr) root->next[s[0] - 'a'] = new node();
+    insert(root->next[s[0] - 'a'], s.substr(1));
+}
+
+int query(node* root, string s) {
+    return s.empty() ? root->val : (root->next[s[0] - 'a'] == nullptr ? 0 : query(root->next[s[0] - 'a'], s.substr(1)));
+}
+
+int main() {
+    node* root = new node();
+    cin >> n;
+    for (int i = 0; i < n; i++) {
+        cin >> op >> s;
+        if (op == 'I') {
+            insert(root, s);
+        } else {
+            cout << query(root, s) << endl;
+        }
+    }
+    delete root;
+    return 0;
+}