20240418

ACMOJ-2179.cpp

@@ -0,0 +1,78 @@
+#include <algorithm>
+#include <cmath>
+#include <cstdio>
+using namespace std;
+template <typename T>
+inline void read(T &t) {
+  t = 0;
+  int ch, f = false;
+  while (ch = getchar(), !((ch >= '0' && ch <= '9') || ch == '-'))
+    ;
+  if (ch == '-') f = true, ch = getchar();
+  t = ch ^ 48;
+  while (ch = getchar(), ch >= '0' && ch <= '9') t = t * 10 + (ch ^ 48);
+  if (f) t = -t;
+}
+template <typename T, typename... Args>
+inline void read(T &t, Args &...args) {
+  read(t);
+  read(args...);
+}
+const int maxn = 500005;
+const int maxm = 200005;
+struct Query {
+  int l, r, id;
+};
+Query q[maxm];
+int n, m, cnt[1000001], tot, a[maxn], res[maxm], bid[maxn];
+inline bool cmp(const Query &a, const Query &b) {
+  return bid[a.l] != bid[b.l] ? bid[a.l] < bid[b.l]
+                              : ((bid[a.l] & 1) ? a.r < b.r : a.r > b.r);
+}
+template <typename T>
+void MergeSort(T *beg, T *end, bool (*cmp)(const T &, const T &)) {
+  if (end - beg <= 1) return;
+  size_t len = end - beg;
+  T *mid = beg + (len >> 1);
+  MergeSort(beg, mid, cmp);
+  MergeSort(mid, end, cmp);
+  T *tmp = new T[len];
+  T *cur_tmp = tmp, *cur_L = beg, *cur_R = mid;
+  while ((cur_L < mid) && (cur_R < end)) {
+    if (cmp(*cur_L, *cur_R))
+      *(cur_tmp++) = *(cur_L++);
+    else
+      *(cur_tmp++) = *(cur_R++);
+  }
+  while (cur_L < mid) *(cur_tmp++) = *(cur_L++);
+  while (cur_R < end) *(cur_tmp++) = *(cur_R++);
+  cur_tmp = tmp;
+  T *cur_dst = beg;
+  while (cur_dst < end) *(cur_dst++) = *(cur_tmp++);
+  delete[] tmp;
+}
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  read(n);
+  for (int i = 1; i <= n; i++) read(a[i]);
+  read(m);
+  for (int i = 1; i <= m; i++) read(q[i].l, q[i].r), q[i].id = i;
+  int blo = sqrt(n);
+  for (int i = 1; i <= n; i++) bid[i] = (i - 1) / blo + 1;
+  MergeSort(q + 1, q + 1 + m, cmp);
+  int l = q[1].l, r = q[1].r;
+  for (int i = l; i <= r; i++) tot += (++cnt[a[i]] == 1);
+  res[q[1].id] = tot;
+  for (int i = 2; i <= m; i++) {
+    Query &Q = q[i];
+    while (l < Q.l) tot -= (--cnt[a[l++]] == 0);
+    while (l > Q.l) tot += (++cnt[a[--l]] == 1);
+    while (r > Q.r) tot -= (--cnt[a[r--]] == 0);
+    while (r < Q.r) tot += (++cnt[a[++r]] == 1);
+    res[Q.id] = tot;
+  }
+  for (int i = 1; i <= m; i++) printf("%d\n", res[i]);
+  return 0;
+}