#1693. 【2022.10.25 联考】成语接龙

https://sjzezoj.com/submission/61821

S2OJ/1693/1693.cpp

@@ -0,0 +1,83 @@
+#include <iostream>
+#include <algorithm>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int n, m, q, c[N << 1], p[N], ans[N << 1], lst[N];
+bool vis[N];
+std::vector<int> g[N << 1], circle;
+
+int dfs1(int u) {
+    if (vis[u]) return u;
+    vis[u] = true;
+    return dfs1(p[u]);
+}
+
+void dfs2(int u, int f, int d) {
+    int x = lst[c[u]];
+    ans[u] = std::min({ans[u], ans[f] + 1, d - x + 1});
+    lst[c[u]] = d;
+    for (int v : g[u]) {
+        if (v == f) continue;
+        dfs2(v, u, d + 1);
+    }
+    lst[c[u]] = x;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> c[i];
+    }
+
+    for (int i = 1; i <= n; i++) {
+        cin >> p[i];
+    }
+
+    int root = dfs1(1);
+    std::fill_n(vis, N, false);
+
+    for (int u = p[root]; u != root; u = p[u]) {
+        circle.emplace_back(u);
+    }
+    circle.emplace_back(root);
+
+    for (int x : circle) {
+        vis[x] = true;
+        c[x + n] = c[x];
+    }
+
+    g[p[root] + n].emplace_back(root);
+    for (int i = 1; i < circle.size(); i++) {
+        g[circle[i]].emplace_back(circle[i - 1]);
+        g[circle[i] + n].emplace_back(circle[i - 1] + n);
+    }
+
+    for (int i = 1; i <= n; i++) {
+        if (vis[i] && vis[p[i]]) continue;
+        g[p[i]].emplace_back(i);
+    }
+
+    std::fill_n(ans, N << 1, 0x3f3f3f3f);
+    ans[root + n] = 1;
+    dfs2(root + n, 0, 1);
+
+    cin >> q;
+
+    while (q--) {
+        int x;
+        cin >> x;
+        cout << ans[x] << endl;
+    }
+
+    return 0;
+}