HDOJ: 2024“钉耙编程”中国大学生算法设计超级联赛（6）

HDOJ/7494.cpp

@@ -0,0 +1,46 @@
+/**
+ * @file 7494.cpp
+ * @author Macesuted ([email protected])
+ * @date 2024-08-05
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define maxn 200005
+
+vector<vector<int>> graph;
+
+void solve(void) {
+    int n;
+    cin >> n;
+    graph.clear(), graph.resize(n + 1);
+    for (int i = 1, x, y; i < n; i++) cin >> x >> y, graph[x].push_back(y), graph[y].push_back(x);
+    for (int i = 1; i <= n; i++) {
+        if (graph[i].size() != 2) continue;
+        int p = graph[i][0], q = graph[i][1], target = n - 1;
+        if (graph[p].size() == 2) {
+            int p2 = graph[p][graph[p][0] == i];
+            if (graph[p2].size() != 1) p = p2, target--;
+        }
+        if (graph[q].size() == 2) {
+            int q2 = graph[q][graph[q][0] == i];
+            if (graph[q2].size() != 1) q = q2, target--;
+        }
+        if ((int)graph[p].size() + (int)graph[q].size() == target) return cout << "Yes" << endl, void();
+    }
+    return cout << "No" << endl, void();
+}
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
+
+    int _;
+    cin >> _;
+    while (_--) solve();
+
+    return 0;
+}

HDOJ/7495.cpp

@@ -0,0 +1,84 @@
+/**
+ * @file 7495.cpp
+ * @author Macesuted ([email protected])
+ * @date 2024-08-05
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define maxn 10005
+
+vector<vector<int>> graph;
+int cnt[maxn], deg[maxn], tot, tot1;
+
+void update(int p, int delt) {
+    if (cnt[p] == deg[p]) (deg[p] == 1 ? tot1 : tot) += delt * (cnt[p] + 1);
+    return;
+}
+
+void solve(void) {
+    int n, m;
+    cin >> n >> m;
+    graph.clear(), graph.resize(n + 1), tot = tot1 = 0;
+    for (int i = 1, x, y; i <= m; i++) cin >> x >> y, graph[x].push_back(y), graph[y].push_back(x);
+    for (int i = 1; i <= n; i++) cnt[i] = 0, deg[i] = graph[i].size();
+    for (int i = 1; i <= n; i++)
+        if (graph[i].size() == 1) cnt[graph[i][0]]++;
+    for (int i = 1; i <= n; i++) update(i, +1);
+    bool vis = false;
+    for (int i = 1; i <= n; i++) {
+        update(i, -1);
+        if (graph[i].empty()) {
+            if (tot + tot1 / 2 == n - 1) cout << i << ' ', vis = true;
+        } else if (graph[i].size() == 1) {
+            int j = graph[i][0];
+            update(graph[i][0], -1), cnt[graph[i][0]]--, deg[graph[i][0]]--, update(graph[i][0], +1);
+            if (graph[j].size() == 2) {
+                int x = graph[j][graph[j][0] == i];
+                update(x, -1), cnt[x]++, update(x, +1);
+            }
+            if (tot + tot1 / 2 == n - 1) cout << i << ' ', vis = true;
+            if (graph[j].size() == 2) {
+                int x = graph[j][graph[j][0] == i];
+                update(x, -1), cnt[x]--, update(x, +1);
+            }
+            update(graph[i][0], -1), cnt[graph[i][0]]++, deg[graph[i][0]]++, update(graph[i][0], +1);
+        } else {
+            for (auto j : graph[i]) {
+                update(j, -1), deg[j]--, update(j, +1);
+                if (graph[j].size() == 2) {
+                    int x = graph[j][graph[j][0] == i];
+                    update(x, -1), cnt[x]++, update(x, +1);
+                }
+            }
+
+            if (tot + tot1 / 2 == n - 1) cout << i << ' ', vis = true;
+
+            for (auto j : graph[i]) {
+                update(j, -1), deg[j]++, update(j, +1);
+                if (graph[j].size() == 2) {
+                    int x = graph[j][graph[j][0] == i];
+                    update(x, -1), cnt[x]--, update(x, +1);
+                }
+            }
+        }
+        update(i, +1);
+    }
+    if (!vis) cout << -1;
+    cout << endl;
+    return;
+}
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
+
+    int _;
+    cin >> _;
+    while (_--) solve();
+
+    return 0;
+}

HDOJ/7502.cpp

@@ -0,0 +1,145 @@
+/**
+ * @file 7502.cpp
+ * @author Macesuted ([email protected])
+ * @date 2024-08-05
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define maxn 500005
+
+int64_t TIME;
+
+struct Func {
+    mutable int64_t k, b;
+
+    Func(void) : k(0), b(0) {}
+    Func(int64_t _k, int64_t _b) : k(_k), b(_b) {}
+
+    int64_t getVal(void) const { return k * TIME + b; }
+
+    bool operator<(const Func& o) const { return getVal() < o.getVal() || (getVal() == o.getVal() && k < o.k); }
+    Func operator+(const Func& o) const { return Func(k + o.k, b + o.b); }
+    Func operator-(const Func& o) const { return Func(k - o.k, b - o.b); }
+    Func& operator+=(const Func& o) { return *this = *this + o; }
+    Func& operator-=(const Func& o) { return *this = *this - o; }
+};
+
+int64_t t[maxn], l[maxn], r[maxn];
+
+multiset<Func> S;
+set<pair<int64_t, Func>> opTim;
+Func ans;
+
+int64_t cross(Func a, Func b) { return (b.b - a.b + 1) / 2; }
+
+void insertL(set<Func>::iterator p) {
+    if (p == S.begin()) return;
+    auto q = p;
+    q--;
+    opTim.emplace(cross(*q, *p), *q);
+    return;
+}
+void eraseL(set<Func>::iterator p) {
+    if (p == S.begin()) return;
+    auto q = p;
+    q--;
+    opTim.erase({cross(*q, *p), *q});
+    return;
+}
+void insertR(set<Func>::iterator p) {
+    auto q = p;
+    q++;
+    if (q == S.end()) return;
+    opTim.emplace(cross(*p, *q), *p);
+    return;
+}
+void eraseR(set<Func>::iterator p) {
+    auto q = p;
+    q++;
+    if (q == S.end()) return;
+    opTim.erase({cross(*p, *q), *p});
+    return;
+}
+
+void print(void) {
+    cerr << "PRINT " << TIME << endl;
+    for (auto [k, b] : S) cerr << '(' << k << ',' << b << ',' << k * TIME + b << ')';
+    cerr << endl;
+    for (auto [tim, Func] : opTim) cerr << "(" << tim << ' ' << Func.k << ' ' << Func.b << ')';
+    cerr << endl;
+    cerr << ans.k << ' ' << ans.b << ' ' << ans.getVal() + S.size() / 2 << endl;
+    return;
+}
+
+void insert(int l, int r) {
+    auto pl = S.lower_bound({-1, l + TIME});
+    if (pl == S.end()) return;
+    if (pl->getVal() > r) {
+        if (pl->k == -1) return;
+        auto it = S.emplace(+1, l - 1 - TIME);
+        it = S.emplace(-1, r + 1 + TIME);
+        insertL(it);
+        ans += Func{+1, l - 1 - TIME};
+        ans -= Func{-1, r + 1 + TIME};
+        return;
+    }
+    auto pr = --S.lower_bound({-1, r + 1 + TIME});
+    if (pl->k == +1) eraseR(pl), ans -= *pl, pl->b = l - 1 - TIME, ans += *pl, insertR(pl), pl++;
+    if (pr->k == -1)
+        eraseL(pr), ans += *pr, pr->b = r + 1 + TIME, ans -= *pr, insertL(pr);
+    else
+        pr++;
+    for (auto i = pl; i != pr;) {
+        eraseL(i);
+        ans += *i, i = S.erase(i);
+        eraseR(i);
+        ans -= *i, i = S.erase(i);
+        if (i != S.end()) insertL(i);
+    }
+    return;
+}
+
+void update(set<pair<int64_t, Func>>::iterator it) {
+    auto p = S.find(it->second);
+    ans -= *p, p = S.erase(p);
+    ans += *p, p = S.erase(p);
+    opTim.erase(it);
+    return;
+}
+
+void solve(void) {
+    int n, q;
+    cin >> n >> q;
+    for (int i = 1; i <= n; i++) cin >> t[i] >> l[i] >> r[i];
+    TIME = 0, S.clear(), S.insert({-1, 0}), S.insert({+1, 0}), opTim.clear(), opTim.emplace(t[n + 1] = INT64_MAX, Func{0, 0});
+    ans = Func(2, 0);
+    for (int i = 1, j = 1; i <= q; i++) {
+        int64_t qt;
+        cin >> qt;
+        while (min(t[j], opTim.begin()->first) <= qt) {
+            if (j <= n && t[j] < opTim.begin()->first)
+                TIME = t[j], insert(l[j], r[j]), j++;
+            else
+                TIME = opTim.begin()->first - 1, update(opTim.begin());
+        }
+        TIME = qt;
+        cout << ans.getVal() + S.size() / 2 << ' ';
+    }
+    cout << endl;
+    return;
+}
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
+
+    int _;
+    cin >> _;
+    while (_--) solve();
+
+    return 0;
+}