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OI-codes/Luogu/problem/P2412/P2412.cpp

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2021-07-04 09:23:29 +00:00
#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;
}