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pojcs101_M01321_chest_grid.cpp

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+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+void log_array(const vector<bool>& arr, const string& name) {
+    clog << name << ": ";
+    for (const auto& cell : arr) {
+        clog << cell << " ";
+    }
+    clog << endl;
+}
+
+vector<vector<bool>> get_grid(const int size) {
+    vector<vector<bool>> grid;
+    for (int _ = 0; _ < size; _++) {
+        string pattern;
+        vector<bool> row;
+        cin >> pattern;
+        for (const char c : pattern) { row.push_back(c != '.'); }
+        grid.push_back(row);
+    }
+    return grid;
+}
+
+long long dfs(const vector<vector<bool>>& grid,
+              const int remaining_chests,
+              const int curr_empty_row,
+              vector<bool>& col_occupation) {
+    const unsigned int size = grid[0].size();
+    if (remaining_chests == 0) { return 1; }
+    if (curr_empty_row >= size) { return 0; }
+    // clog << "curr_empty_row: " << curr_empty_row << endl;
+    // log_array(col_occupation, "col_occupation");
+    long long ans = 0;
+    for (int col = 0; col < size; col++) { // 这行放
+        if (!grid[curr_empty_row][col]) { continue; }
+        if (col_occupation[col]) { continue; }
+        // vector<bool> new_col_occupation(col_occupation);
+        col_occupation[col] = true;
+        ans += dfs(grid, remaining_chests - 1, curr_empty_row + 1, col_occupation);
+        col_occupation[col] = false;
+    }
+    ans += dfs(grid, remaining_chests, curr_empty_row + 1, col_occupation); // 不在这行放
+    return ans;
+}
+
+long long dfs(const vector<vector<bool>>& grid,
+              const int remaining_chests,
+              const int curr_empty_row = 0) {
+    vector<bool> col_occupation(grid[0].size(), false);
+    return dfs(grid, remaining_chests, curr_empty_row, col_occupation);
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int size, chest_count;
+    while (cin >> size >> chest_count) {
+        if (size < 0) { break; }
+        vector<vector<bool>> grid = get_grid(size);
+        cout << dfs(grid, chest_count) << endl;
+    }
+    // cin >> size;
+    // chest_count = size;
+    // const vector<vector<bool>> grid = get_grid(size);
+    // cout << dfs(grid, chest_count) << endl;
+
+    return 0;
+}