P1197 [JSOI2008] 星球大战

https://www.luogu.com.cn/record/77044997

Luogu/P1197/P1197.cpp

@@ -0,0 +1,84 @@
+#include <iostream>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 4e5 + 5;
+
+int n, m, k, a[N], fa[N], ans[N];
+bool vis[N], del[N];
+std::vector<int> g[N];
+
+int find(int x) {
+    return fa[x] == x ? x : fa[x] = find(fa[x]);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 0, x, y; i < m; i++) {
+        cin >> x >> y;
+
+        g[x].push_back(y);
+        g[y].push_back(x);
+    }
+
+    for (int i = 0; i < n; i++) fa[i] = i;
+
+    cin >> k;
+
+    for (int i = 1; i <= k; i++) {
+        cin >> a[i];
+
+        del[a[i]] = true;
+    }
+
+    for (int i = 0; i < n; i++) {
+        if (!del[i]) {
+            for (int v : g[i]) {
+                if (!del[v]) {
+                    int f1 = find(i),
+                        f2 = find(v);
+
+                    fa[f1] = f2;
+                }
+            }
+        }
+    }
+
+    int cnt = 0;
+    for (int i = 0; i < n; i++) {
+        if (fa[i] == i && !del[i]) cnt++;
+    }
+    ans[k] = cnt;
+
+    for (int i = k; i; i--) {
+        del[a[i]] = false;
+        cnt++;
+
+        for (int v : g[a[i]]) {
+            if (!del[v]) {
+                int f1 = find(a[i]),
+                    f2 = find(v);
+
+                if (f1 != f2) {
+                    fa[f1] = f2;
+                    cnt--;
+                }
+            }
+        }
+
+        ans[i - 1] = cnt;
+    }
+
+    for (int i = 0; i <= k; i++) {
+        cout << ans[i] << endl;
+    }
+
+    return 0;
+}