P4158 [SCOI2009]粉刷匠

https://www.luogu.com.cn/record/86131090

Luogu/P4158/P4158.cpp

@@ -0,0 +1,64 @@
+#include <iostream>
+#include <utility>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 55;
+
+int n, m, t, f[N][N][2], g[2505];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m >> t;
+
+    for (int i = 1; i <= n; i++) {
+        int last = 0;
+        std::string s;
+        std::vector<std::pair<int, int>> blocks;
+
+        cin >> s;
+
+        for (int j = 0; j < m; j++) {
+            if (s[j] != s[last]) {
+                blocks.emplace_back(last + 1, j);
+                last = j;
+            }
+        }
+
+        if (last != m) {
+            blocks.emplace_back(last + 1, m);
+        }
+
+        for (int i = 1; i <= blocks.size(); i++) {
+            const auto &block = blocks[i - 1];
+
+            for (int j = blocks.size(); j; j--) {
+                // 不染色时直接从前一格转移
+                f[i][j][0] = std::max(f[i - 1][j][0], f[i - 1][j][1]);
+
+                // 刷成和上个格子一样的颜色
+                f[i][j][1] = std::max(f[i - 1][j - 1][0], f[i - 1][j - 1][1]) + block.second - block.first + 1;
+
+                // 刷成和上上个格子一样的颜色
+                if (i >= 2) {
+                    f[i][j][1] = std::max(f[i][j][1], f[i - 2][j][1] + block.second - block.first + 1);
+                }
+            }
+        }
+
+        for (int j = t; j >= 0; j--) {
+            for (int k = 0; k <= std::min(j, static_cast<int>(blocks.size())); k++) {
+                g[j] = std::max(g[j], g[j - k] + std::max(f[blocks.size()][k][0], f[blocks.size()][k][1]));
+            }
+        }
+    }
+
+    cout << g[t] << endl;
+
+    return 0;
+}