Added CF1730F

contest/cf1730/F.cpp

@@ -0,0 +1,82 @@
+#include <bits/stdc++.h>
+
+using ll = long long int;
+
+const int MAXN = 5e3 + 19, B = 8;
+const int INF = 1e9;
+
+int n, k;
+int dp[MAXN][1 << B], p[MAXN], pos[MAXN];
+
+void chkmin(auto &a, const auto &b) {
+    if (a > b) {
+        a = b;
+    }
+}
+
+struct BIT {
+    int tr[MAXN];
+    void update(int x, int k) {
+        for (; x <= n; x += x & -x) {
+            tr[x] += k;
+        }
+    }
+    int query(int x) {
+        int res = 0;
+        for (; x; x -= x & -x) {
+            res += tr[x];
+        }
+        return res;
+    }
+} mt;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    std::cin.tie(nullptr);
+
+    std::cin >> n >> k;
+    for (int i = 1; i <= n; ++i) {
+        std::cin >> p[i];
+        pos[p[i]] = i;
+    }
+
+    for (int i = 1; i <= n + 1; ++i) {
+        std::fill(dp[i], dp[i] + (1 << k), INF);
+    }
+    dp[1][0] = 0;
+    for (int i = 1; i <= n; ++i) {
+        for (int S = 0; S < (1 << k); ++S) {
+            int tot = i - 1;
+            for (int j = 1; j <= k && i + j <= n; ++j) {
+                if (S & (1 << (j - 1))) {
+                    tot += 1;
+                    mt.update(pos[i + j], 1);
+                }
+            }
+
+            int nxt = 1;
+            while (S & (1 << (nxt - 1))) {
+                nxt += 1;
+            }
+            chkmin(dp[i + nxt][S >> nxt], dp[i][S] + tot - mt.query(pos[i]));
+
+            for (int j = 1; j <= k && i + j <= n; ++j) {
+                if (!(S & (1 << (j - 1)))) {
+                    chkmin(dp[i][S | (1 << (j - 1))], dp[i][S] + tot - mt.query(pos[i + j]));
+                }
+            }
+
+            for (int j = 1; j <= k && i + j <= n; ++j) {
+                if (S & (1 << (j - 1))) {
+                    tot += 1;
+                    mt.update(pos[i + j], -1);
+                }
+            }
+        }
+        mt.update(pos[i], 1);
+    }
+
+    std::cout << dp[n + 1][0] << '\n';
+
+    return 0;
+}