mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-12-13 05:46:26 +00:00
90 lines
1.9 KiB
C++
90 lines
1.9 KiB
C++
#include <algorithm>
|
|
#include <iostream>
|
|
#include <vector>
|
|
|
|
using std::cin;
|
|
using std::cout;
|
|
using std::endl;
|
|
|
|
const int N = 200005;
|
|
|
|
int n, m, l, r, k, a[N];
|
|
std::vector<int> nums;
|
|
|
|
// Helpers
|
|
int find(int);
|
|
|
|
// Segment Tree
|
|
int cnt, root[N];
|
|
int build(int, int);
|
|
int insert(int, int, int, int);
|
|
int query(int, int, int, int, int);
|
|
|
|
int main() {
|
|
cin >> n >> m;
|
|
for (int i = 1; i <= n; i++) {
|
|
cin >> a[i];
|
|
nums.push_back(a[i]);
|
|
}
|
|
std::sort(nums.begin(), nums.end());
|
|
nums.erase(std::unique(nums.begin(), nums.end()), nums.end());
|
|
root[0] = build(0, nums.size() - 1);
|
|
for (int i = 1; i <= n; i++) {
|
|
root[i] = insert(root[i - 1], 0, nums.size() - 1, find(a[i]));
|
|
}
|
|
while (m--) {
|
|
cin >> l >> r >> k;
|
|
cout << nums[query(root[r], root[l - 1], 0, nums.size() - 1, k)] << endl;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
// === Helpers ===
|
|
|
|
inline int find(int x) {
|
|
return std::lower_bound(nums.begin(), nums.end(), x) - nums.begin();
|
|
}
|
|
|
|
// === Segment Tree ===
|
|
|
|
struct node {
|
|
int l, r, c;
|
|
|
|
node()
|
|
: l(0), r(0), c(0) {}
|
|
} tr[N << 5];
|
|
|
|
int build(int l, int r) {
|
|
int p = ++cnt;
|
|
if (l == r) return p;
|
|
int mid = l + r >> 1;
|
|
tr[p].l = build(l, mid);
|
|
tr[p].r = build(mid + 1, r);
|
|
return p;
|
|
}
|
|
|
|
int insert(int p, int l, int r, int x) {
|
|
int q = ++cnt;
|
|
tr[q] = tr[p];
|
|
if (l == r) {
|
|
tr[q].c++;
|
|
return q;
|
|
}
|
|
int mid = l + r >> 1;
|
|
if (x <= mid) {
|
|
tr[q].l = insert(tr[p].l, l, mid, x);
|
|
} else {
|
|
tr[q].r = insert(tr[p].r, mid + 1, r, x);
|
|
}
|
|
tr[q].c = tr[tr[q].l].c + tr[tr[q].r].c;
|
|
return q;
|
|
}
|
|
|
|
int query(int q, int p, int l, int r, int k) {
|
|
if (l == r) return l;
|
|
int c = tr[tr[q].l].c - tr[tr[p].l].c;
|
|
int mid = l + r >> 1;
|
|
if (k <= c) return query(tr[q].l, tr[p].l, l, mid, k);
|
|
return query(tr[q].r, tr[p].r, mid + 1, r, k - c);
|
|
}
|