SP3267 DQUERY - D-query

R65783190

Luogu/SP3267/SP3267.cpp

@@ -0,0 +1,93 @@
+#include <algorithm>
+#include <iostream>
+#include <map>
+#include <vector>
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+const int N = 300005;
+
+int n, q, a[N], pre[N];
+std::map<int, int> map;
+
+// Segment Tree
+int cnt, root[N];
+int build(int, int);
+int insert(int, int, int);
+int query(int, int);
+
+int main() {
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+    root[0] = build(1, n);
+    for (int i = 1; i <= n; i++) {
+        if (!map.count(a[i])) {
+            root[i] = insert(root[i - 1], i, 1);
+        } else {
+            int tmp = insert(root[i - 1], map[a[i]], -1);
+            root[i] = insert(tmp, i, 1);
+        }
+        map[a[i]] = i;
+    }
+    cin >> q;
+    while (q--) {
+        int l, r;
+        cin >> l >> r;
+        cout << query(root[r], l) << endl;
+    }
+    return 0;
+}
+
+// === Segment Tree ===
+
+struct node {
+    int l, r, c;
+    int lid, rid;
+
+    node()
+        : l(0), r(0), c(0), lid(0), rid(0) {}
+    node(int _l, int _r)
+        : l(_l), r(_r), c(0), lid(0), rid(0) {}
+} tr[N << 7];
+
+inline void pushup(int u) {
+    tr[u].c = tr[tr[u].lid].c + tr[tr[u].rid].c;
+}
+
+int build(int l, int r) {
+    int p = ++cnt;
+    tr[p] = node(l, r);
+    if (l == r) return p;
+    int mid = l + r >> 1;
+    tr[p].lid = build(l, mid);
+    tr[p].rid = build(mid + 1, r);
+    return p;
+}
+
+int insert(int p, int x, int v) {
+    int q = ++cnt;
+    tr[q] = tr[p];
+    if (tr[q].l == tr[q].r) {
+        tr[q].c += v;
+        return q;
+    }
+    int mid = tr[q].l + tr[q].r >> 1;
+    if (x <= mid) {
+        tr[q].lid = insert(tr[p].lid, x, v);
+    } else {
+        tr[q].rid = insert(tr[p].rid, x, v);
+    }
+    pushup(q);
+    return q;
+}
+
+int query(int u, int x) {
+    if (tr[u].l == tr[u].r) return tr[u].c;
+    int mid = tr[u].l + tr[u].r >> 1;
+    if (x <= mid) return tr[tr[u].rid].c + query(tr[u].lid, x);
+    return query(tr[u].rid, x);
+}