P3694 邦邦的大合唱站队

https://www.luogu.com.cn/record/77411977

Luogu/P3694/P3694.cpp

@@ -0,0 +1,47 @@
+#include <iostream>
+#include <array>
+#include <limits>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5,
+          M = 25;
+
+int n, m, f[(1 << 20) + 5];
+std::array<int, M> s[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+
+        s[i] = s[i - 1];
+        s[i][x]++;
+    }
+
+    std::fill(f + 1, f + (1 << m), std::numeric_limits<int>::max());
+
+    for (int i = 0; i < 1 << m; i++) {
+        int cnt = 0;
+        for (int j = 0; j < m; j++) {
+            if (i & (1 << j)) cnt += s[n][j + 1];
+        }
+
+        for (int j = 0; j < m; j++) {
+            if (i & (1 << j)) continue;
+
+            int l = cnt, r = l + s[n][j + 1];
+            f[i | (1 << j)] = std::min(f[i | (1 << j)], f[i] + r - l - (s[r][j + 1] - s[l][j + 1]));
+        }
+    }
+
+    cout << f[(1 << m) - 1] << endl;
+
+    return 0;
+}