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P3834 【模板】可持久化线段树 2

Browse Source 
https://www.luogu.com.cn/record/103042247
This commit is contained in:
Baoshuo Ren 2023-02-26 08:53:30 +08:00
parent b1fdc7d76e
commit 9bc774e447
Signed by: baoshuo
GPG Key ID: 00CB9680AB29F51A
1 changed files with 21 additions and 11 deletions
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32
Luogu/P3834/P3834.cpp
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@ -1,5 +1,6 @@
#include <iostream> #include <iostream>
#include <algorithm> #include <algorithm>
#include <iterator>
#include <vector> #include <vector>
using std::cin; using std::cin;
@ -16,12 +17,16 @@ struct node {
int l, r, c; int l, r, c;
} tr[N << 5]; } tr[N << 5];
int find(int x) {
return std::distance(nums.begin(), std::lower_bound(nums.begin(), nums.end(), x));
}
int build(int l, int r) { int build(int l, int r) {
int p = ++cnt; int p = ++cnt;
if (l == r) return p; if (l == r) return p;
int mid = l + r >> 1; int mid = (l + r) >> 1;
tr[p].l = build(l, mid); tr[p].l = build(l, mid);
tr[p].r = build(mid + 1, r); tr[p].r = build(mid + 1, r);
@ -31,30 +36,35 @@ int build(int l, int r) {
int insert(int p, int l, int r, int x) { int insert(int p, int l, int r, int x) {
int q = ++cnt; int q = ++cnt;
tr[q] = tr[p]; tr[q] = tr[p];
if (l == r) { if (l == r) {
tr[q].c++; tr[q].c++;
return q; return q;
} }
int mid = l + r >> 1; int mid = (l + r) >> 1;
if (x <= mid) tr[q].l = insert(tr[q].l, l, mid, x); if (x <= mid) tr[q].l = insert(tr[p].l, l, mid, x);
else tr[q].r = insert(tr[q].r, mid + 1, r, 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; tr[q].c = tr[tr[q].l].c + tr[tr[q].r].c;
return q; return q;
} }
int query(int p, int q, int l, int r, int x) { int query(int p, int q, int l, int r, int k) {
if (l == r) return l; if (l == r) return l;
int c = tr[tr[p].l].c - tr[tr[q].l].c;
int mid = l + r >> 1;
if (x <= c) return query(tr[p].l, tr[q].l, l, mid, x); int mid = (l + r) >> 1;
return query(tr[p].r, tr[q].r, mid + 1, r, x - c);
int c = tr[tr[q].l].c - tr[tr[p].l].c;
if (c >= k) return query(tr[p].l, tr[q].l, l, mid, k);
return query(tr[p].r, tr[q].r, mid + 1, r, k - c);
} }
int main() { int main() {
@ -75,7 +85,7 @@ int main() {
root[0] = build(0, nums.size() - 1); root[0] = build(0, nums.size() - 1);
for (int i = 1; i <= n; i++) { for (int i = 1; i <= n; i++) {
root[i] = insert(root[i - 1], 0, nums.size() - 1, std::lower_bound(nums.begin(), nums.end(), a[i]) - nums.begin()); root[i] = insert(root[i - 1], 0, nums.size() - 1, find(a[i]));
} }
while (m--) { while (m--) {
@ -83,7 +93,7 @@ int main() {
cin >> l >> r >> k; cin >> l >> r >> k;
cout << nums.at(query(root[r], root[l - 1], 0, nums.size() - 1, k)) << endl; cout << nums[query(root[l - 1], root[r], 0, nums.size() - 1, k)] << endl;
} }
return 0; return 0;