P2412 查单词

R52376877

Luogu/problem/P2412/P2412.cpp

@@ -0,0 +1,65 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+struct node {
+    int l, r;
+    string s;
+
+    node() {
+        l = r = 0;
+        s = "";
+    }
+    node(int _l, int _r) {
+        l = _l;
+        r = _r;
+        s = "";
+    }
+} tr[50005 << 2];
+int n, m, x, y;
+string a[50005], b[50005];
+map<string, string> m1;
+
+void pushup(int u) {
+    tr[u].s = max(tr[u << 1].s, tr[u << 1 | 1].s);
+}
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+    if (l == r) {
+        tr[u].s = a[l];
+        return;
+    }
+    int mid = l + r >> 1;
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+    pushup(u);
+}
+
+string query(int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        return tr[u].s;
+    }
+    int mid = tr[u].l + tr[u].r >> 1;
+    string s;
+    if (l <= mid) s = max(s, query(u << 1, l, r));
+    if (r > mid) s = max(s, query(u << 1 | 1, l, r));
+    return s;
+}
+
+int main() {
+    cin >> n >> m;
+    for (int i = 1; i <= n; i++) {
+        cin >> b[i];
+        for (char c : b[i]) {
+            a[i].push_back(tolower(c));
+        }
+        m1[a[i]] = b[i];
+    }
+    build(1, 1, n);
+    for (int i = 0; i < m; i++) {
+        cin >> x >> y;
+        cout << m1[query(1, x, y)] << endl;
+    }
+    return 0;
+}