142. 前缀统计

https://www.acwing.com/problem/content/submission/code_detail/8017084/

AcWing/142/142.cpp

@@ -0,0 +1,51 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, ans;
+string s;
+
+struct node {
+    int size;
+    node* next[26];
+
+    ~node() {
+        for (auto& i : next) {
+            delete i;
+        }
+    }
+};
+
+void insert(node* root, string s) {
+    if (s.empty()) {
+        root->size++;
+        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) {
+    if (s.empty()) return root->size;
+    if (root->next[s[0] - 'a'] == nullptr) return 0;
+    return query(root->next[s[0] - 'a'], s.substr(1));
+}
+
+int main() {
+    node* root = new node();
+    cin >> n >> m;
+    for (int i = 1; i <= n; i++) {
+        cin >> s;
+        insert(root, s);
+    }
+    for (int i = 1; i <= m; i++) {
+        ans = 0;
+        cin >> s;
+        for (int j = 1; j <= s.size(); j++) {
+            ans += query(root, s.substr(0, j));
+        }
+        cout << ans << endl;
+    }
+    delete root;
+    return 0;
+}