记录一下
```cpp
#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace std;
using namespace __gnu_pbds;
const int R = 5e4 + 10;
tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update> t[R * 4];
int tot, n, a[R];
#define lc(k) (k << 1)
#define rc(k) (k << 1 | 1)
#define mid ((l + r) >> 1)
void build(int k, int l, int r)
{
t[k].insert(make_pair(-2147483647, -1));
t[k].insert(make_pair(2147483647, R));
for (int i = l; i <= r; ++i)
{
t[k].insert(make_pair(a[i], i));
}
if (l == r)
{
return;
}
build(lc(k), l, mid);
build(rc(k), mid + 1, r);
}
int rankx(int k, int l, int r, int x, int y, int v)
{
if (x <= l && y >= r)
{
return t[k].order_of_key(make_pair(v, 0)) - 1;
}
int res = 0;
if (x <= mid)
{
res = rankx(lc(k), l, mid, x, y, v);
}
if (y > mid)
{
res += rankx(rc(k), mid + 1, r, x, y, v);
}
return res;
}
int kth(int x, int y, int k)
{
int res = 0, l = 0, r = 1e8;
while (l <= r)
{
if (rankx(1, 1, n, x, y, mid) + 1 <= k)
{
res = mid;
l = mid + 1;
}
else
{
r = mid - 1;
}
}
return res;
}
void update(int k, int l, int r, int p, int v)
{
t[k].erase(t[k].find(make_pair(a[p], p)));
t[k].insert(make_pair(v, p));
if (l == r)
{
return;
}
if (p <= mid)
{
update(lc(k), l, mid, p, v);
}
else
{
update(rc(k), mid + 1, r, p, v);
}
}
int pre(int k, int l, int r, int x, int y, int v)
{
if (x <= l && y >= r)
{
return (*(--t[k].lower_bound(make_pair(v, -1)))).first;
}
int res = -2147483647;
if (x <= mid)
{
res = pre(lc(k), l, mid, x, y, v);
}
if (y > mid)
{
res = max(pre(rc(k), mid + 1, r, x, y, v), res);
}
return res;
}
int succ(int k, int l, int r, int x, int y, int v)
{
if (x <= l && y >= r)
{
return (*(t[k].upper_bound(make_pair(v, -1)))).first;
}
int res = 2147483647;
if (x <= mid)
{
res = succ(lc(k), l, mid, x, y, v);
}
if (y > mid)
{
res = min(succ(rc(k), mid + 1, r, x, y, v), res);
}
return res;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int m, i, l, r, k, p;
cin >> n >> m;
for (i = 1; i <= n; ++i)
{
cin >> a[i];
}
build(1, 1, n);
char op;
while (m--)
{
cin >> op >> l >> r;
if (op == '1')
{
cin >> k;
cout << rankx(1, 1, n, l, r, k) + 1 << '\n';
}
else if (op == '2')
{
cin >> k;
cout << kth(l, r, k) << '\n';
}
else if (op == '3')
{
p = l, k = r;
update(1, 1, n, p, k);
a[p] = k;
}
else if (op == '4')
{
cin >> k;
cout << pre(1, 1, n, l, r, k) << '\n';
}
else
{
cin >> k;
cout << succ(1, 1, n, l, r, k) << '\n';
}
}
return 0;
}
```
by Bodhi @ 2023-10-01 17:59:21