Init

ACMOJ-2081.cpp

@@ -0,0 +1,60 @@
+#include <algorithm>
+#include <cstdio>
+#include <cstring>
+using namespace std;
+typedef long long LL;
+const LL kInf = 0x3f3f3f3f3f3f3f3fll;
+const int kMaxN = 5010;
+int n, k, h[kMaxN], tot_val, t[kMaxN];
+LL cnt[kMaxN], w[kMaxN][kMaxN], dp[kMaxN][2];
+int d[kMaxN][kMaxN];
+void Modify(int p, LL v) {
+  for (; p <= tot_val; p += p & (-p)) cnt[p] += v;
+}
+LL Query(int p) {
+  LL ret = 0;
+  for (; p > 0; p -= p & (-p)) ret += cnt[p];
+  return ret;
+}
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  scanf("%d%d", &n, &k);
+  //	printf("%d %d\n",n,k);
+  for (int i = 1; i <= n; i++) {
+    scanf("%d", &h[i]);
+    t[i] = h[i];
+  }
+  sort(t + 1, t + 1 + n);
+  int pos = 0;
+  t[0] = -kInf;
+  for (int i = 1; i <= n; i++) {
+    if (t[i] != t[pos]) t[++pos] = t[i];
+  }
+  tot_val = pos;
+  for (int i = 1; i <= n; i++) h[i] = lower_bound(t + 1, t + 1 + n, h[i]) - t;
+  for (int i = 1; i <= n; i++) {
+    Modify(h[i], 1);
+    for (int j = i + 1; j <= n; j++) {
+      w[i][j] = w[i][j - 1] + j - i - Query(h[j]);
+      Modify(h[j], 1);
+    }
+    memset(cnt, 0, sizeof(cnt));
+  }
+  memset(dp, 0x3f, sizeof(dp));
+  dp[0][0] = 0;
+  for (int j = 1; j <= k; j++) {
+    d[n + 1][j] = n;
+    for (int i = n; i >= j; i--) {
+      for (int t = d[i][j - 1]; t <= d[i + 1][j]; t++) {
+        if (dp[t][(j - 1) & 1] + w[t + 1][i] < dp[i][j & 1]) {
+          dp[i][j & 1] = dp[t][(j - 1) & 1] + w[t + 1][i];
+          d[i][j] = t;
+        }
+      }
+    }
+  }
+  printf("%lld\n", dp[n][k & 1]);
+  return 0;
+}