#1537. 【2022.09.05NOIP模拟题】国境线

https://sjzezoj.com/submission/55837

S2OJ/1537/1537.cpp

@@ -0,0 +1,75 @@
+#include <iostream>
+#include <cstring>
+#include <queue>
+#include <tuple>
+#include <utility>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 3005;
+const int d[][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
+
+int n, m, k, q, id[N][N], dist[N][N], ans;
+std::queue<std::pair<int, int>> queue;
+bool g[N][N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    memset(dist, -0x3f, sizeof(dist));
+
+    cin >> n >> m >> k;
+
+    for (int i = 1, x, y; i <= k; i++) {
+        cin >> x >> y;
+
+        id[x][y] = i;
+        dist[x][y] = 0;
+
+        queue.emplace(x, y);
+    }
+
+    cin >> q;
+
+    for (int i = 1, x, y; i <= q; i++) {
+        cin >> x >> y;
+
+        g[x][y] = true;
+    }
+
+    while (!queue.empty()) {
+        int x, y;
+
+        std::tie(x, y) = queue.front();
+        queue.pop();
+
+        for (const auto &d : d) {
+            int xx = x + d[0],
+                yy = y + d[1];
+
+            if (xx < 1 || xx > n || yy < 1 || yy > m || g[xx][yy]) continue;
+
+            if (id[xx][yy] == 0) {
+                id[xx][yy] = id[x][y];
+                dist[xx][yy] = dist[x][y] + 1;
+
+                queue.emplace(xx, yy);
+            } else if (dist[x][y] + 1 == dist[xx][yy] && id[x][y] != id[xx][yy]) {
+                id[xx][yy] = -1;
+            }
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= m; j++) {
+            if (id[i][j] == -1) ans++;
+        }
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}