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https://git.sb/baoshuo/OI-codes.git
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94 lines
1.8 KiB
C++
94 lines
1.8 KiB
C++
#include <algorithm>
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#include <iostream>
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#include <map>
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#include <vector>
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using std::cin;
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using std::cout;
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using std::endl;
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const int N = 300005;
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int n, q, a[N], pre[N];
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std::map<int, int> map;
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// Segment Tree
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int cnt, root[N];
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int build(int, int);
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int insert(int, int, int);
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int query(int, int);
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int main() {
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cin >> n;
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for (int i = 1; i <= n; i++) {
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cin >> a[i];
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}
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root[0] = build(1, n);
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for (int i = 1; i <= n; i++) {
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if (!map.count(a[i])) {
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root[i] = insert(root[i - 1], i, 1);
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} else {
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int tmp = insert(root[i - 1], map[a[i]], -1);
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root[i] = insert(tmp, i, 1);
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}
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map[a[i]] = i;
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}
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cin >> q;
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while (q--) {
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int l, r;
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cin >> l >> r;
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cout << query(root[r], l) << endl;
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}
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return 0;
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}
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// === Segment Tree ===
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struct node {
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int l, r, c;
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int lid, rid;
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node()
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: l(0), r(0), c(0), lid(0), rid(0) {}
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node(int _l, int _r)
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: l(_l), r(_r), c(0), lid(0), rid(0) {}
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} tr[N << 7];
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inline void pushup(int u) {
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tr[u].c = tr[tr[u].lid].c + tr[tr[u].rid].c;
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}
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int build(int l, int r) {
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int p = ++cnt;
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tr[p] = node(l, r);
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if (l == r) return p;
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int mid = l + r >> 1;
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tr[p].lid = build(l, mid);
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tr[p].rid = build(mid + 1, r);
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return p;
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}
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int insert(int p, int x, int v) {
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int q = ++cnt;
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tr[q] = tr[p];
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if (tr[q].l == tr[q].r) {
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tr[q].c += v;
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return q;
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}
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int mid = tr[q].l + tr[q].r >> 1;
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if (x <= mid) {
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tr[q].lid = insert(tr[p].lid, x, v);
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} else {
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tr[q].rid = insert(tr[p].rid, x, v);
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}
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pushup(q);
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return q;
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}
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int query(int u, int x) {
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if (tr[u].l == tr[u].r) return tr[u].c;
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int mid = tr[u].l + tr[u].r >> 1;
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if (x <= mid) return tr[tr[u].rid].c + query(tr[u].lid, x);
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return query(tr[u].rid, x);
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}
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