#6284. 数列分块入门 8

https://loj.ac/s/1466227

LibreOJ/6284/6284.cpp

@@ -0,0 +1,94 @@
+#include <cmath>
+#include <cstring>
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int n, c, t, a[N], st[N], ed[N], pos[N], rep[N];
+
+inline void pushdown(int x) {
+    if (rep[x] != -1) {
+        for (int i = st[x]; i <= ed[x]; i++) a[i] = rep[x];
+        rep[x] = -1;
+    }
+}
+
+int solve(int l, int r, int c) {
+    int p = pos[l],
+        q = pos[r];
+    int res = 0;
+
+    if (p == q) {
+        pushdown(p);
+        for (int i = l; i <= r; i++) {
+            if (a[i] == c) res++;
+            a[i] = c;
+        }
+
+        return res;
+    }
+
+    pushdown(p);
+    for (int i = l; i <= ed[p]; i++) {
+        if (a[i] == c) res++;
+        a[i] = c;
+    }
+
+    pushdown(q);
+    for (int i = st[q]; i <= r; i++) {
+        if (a[i] == c) res++;
+        a[i] = c;
+    }
+
+    for (int i = p + 1; i <= q - 1; i++) {
+        if (rep[i] != -1) {
+            if (rep[i] == c) res += ed[i] - st[i] + 1;
+        } else {
+            for (int j = st[i]; j <= ed[i]; j++) {
+                if (a[j] == c) res++;
+                a[j] = c;
+            }
+        }
+        rep[i] = c;
+    }
+
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    memset(rep, 0xff, sizeof(rep));
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+
+    t = std::sqrt(n);
+
+    for (c = 1;; c++) {
+        st[c] = (c - 1) * t + 1;
+        ed[c] = std::min(n, c * t);
+
+        if (c * t >= n) break;
+    }
+
+    for (int i = 1; i <= c; i++) {
+        for (int j = st[i]; j <= ed[i]; j++) {
+            pos[j] = i;
+        }
+    }
+
+    for (int i = 1, l, r, c; i <= n; i++) {
+        cin >> l >> r >> c;
+        cout << solve(l, r, c) << endl;
+    }
+
+    return 0;
+}