T263133 拆网线

https://www.luogu.com.cn/record/85559526

Luogu/T262837/T262837.cpp

@@ -0,0 +1,119 @@
+#include <iostream>
+#include <queue>
+#include <stack>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1005;
+
+int n, m, color[N], ans;
+int cnt, id[N];
+bool vis[N];
+std::vector<int> g[N];
+std::unordered_set<int> p[N];
+
+bool dfs1(int u, int c) {
+    color[u] = c;
+
+    for (int v : g[u]) {
+        if (color[v]) {
+            if (color[v] == c) return false;
+        } else if (!dfs1(v, 3 - c)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool check() {
+    for (int i = 1; i <= n; i++) {
+        if (!color[i]) {
+            if (!dfs1(i, 1)) return false;
+        }
+    }
+
+    return true;
+}
+
+void dfs2(int u, int x) {
+    id[u] = x;
+    p[x].insert(u);
+
+    for (int v : g[u]) {
+        if (!id[v]) dfs2(v, x);
+    }
+}
+
+int bfs(int x) {
+    std::fill_n(vis, N, false);
+
+    int res = 0;
+
+    std::queue<std::pair<int, int>> q;
+
+    q.emplace(x, 0);
+    vis[x] = true;
+
+    while (!q.empty()) {
+        auto e = q.front();
+        q.pop();
+
+        int u = e.first,
+            w = e.second;
+
+        res = std::max(res, w);
+
+        for (int v : g[u]) {
+            if (vis[v]) continue;
+            vis[v] = true;
+
+            q.emplace(v, w + 1);
+        }
+    }
+
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    for (int i = 1, u, v; i <= m; i++) {
+        cin >> u >> v;
+
+        g[u].emplace_back(v);
+        g[v].emplace_back(u);
+    }
+
+    if (!check()) {
+        cout << -1 << endl;
+
+        exit(0);
+    }
+
+    for (int i = 1; i <= n; i++) {
+        if (!id[i]) dfs2(i, ++cnt);
+    }
+
+    for (int i = 1; i <= cnt; i++) {
+        int res = 0;
+
+        for (const int &x : p[i]) {
+            res = std::max(res, bfs(x));
+        }
+
+        ans += res;
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}

Luogu/T263082/T263082.cpp

@@ -0,0 +1,42 @@
+#include <iostream>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int n, a[N], b[N];
+std::vector<std::pair<int, int>> ans;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+
+        b[i] = a[i] - a[i - 1];
+    }
+
+    b[n + 1] = -a[n];
+
+    for (int i = 1, j = 1; i <= n + 1; i++) {
+        while (b[i] < 0) {
+            while (j < i && b[j] <= 0) j++;
+            b[j]--, b[i]++;
+            ans.emplace_back(j, i - 1);
+        }
+    }
+
+    cout << ans.size() << endl;
+
+    for (const auto &e : ans) {
+        cout << e.first << ' ' << e.second << endl;
+    }
+
+    return 0;
+}

Luogu/T263132/T263132.cpp

@@ -0,0 +1,74 @@
+#include <iostream>
+#include <algorithm>
+#include <queue>
+#include <utility>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 50005;
+
+int n, k;
+long long m, sum;
+std::pair<long long, long long> a[N];
+std::priority_queue<long long, std::vector<long long>, std::greater<long long>> q;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> k >> m;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i].first >> a[i].second;
+    }
+
+    std::sort(a + 1, a + n + 1, [](auto a, auto b) {
+        return a.second < b.second;
+    });
+
+    for (int i = 1; i <= k; i++) {
+        sum += a[i].second;
+
+        q.push(a[i].first - a[i].second);
+
+        if (sum > m) {
+            cout << i - 1 << endl;
+
+            exit(0);
+        } else if (i == n) {
+            cout << n << endl;
+
+            exit(0);
+        }
+    }
+
+    std::sort(a + k + 1, a + n + 1, [](auto a, auto b) {
+        return a.first < b.first;
+    });
+
+    for (int i = k + 1; i <= n; i++) {
+        auto x = q.top();
+
+        sum += a[i].first;
+
+        if (a[i].second + x < a[i].first) {
+            q.pop();
+
+            auto y = a[i].first - a[i].second;
+            q.push(y);
+            sum += x - y;
+        }
+
+        if (sum > m) {
+            cout << i - 1 << endl;
+
+            exit(0);
+        }
+    }
+
+    cout << n << endl;
+
+    return 0;
+}

Luogu/T263133/T263133.cpp

@@ -0,0 +1,69 @@
+#include <iostream>
+#include <cmath>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+
+int t, n, k;
+std::vector<int> top, g[N];
+bool vis[N];
+
+void dfs(int u) {
+    vis[u] = true;
+
+    for (int v : g[u]) {
+        if (!vis[v]) dfs(v);
+    }
+
+    top.push_back(u);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> t;
+
+    while (t--) {
+        top.clear();
+        std::fill_n(g, N, std::vector<int>());
+        std::fill_n(vis, N, false);
+
+        int ans = 0;
+
+        cin >> n >> k;
+
+        for (int i = 2, x; i <= n; i++) {
+            cin >> x;
+
+            g[i].push_back(x);
+            g[x].push_back(i);
+        }
+
+        dfs(1);
+
+        std::fill_n(vis, N, false);
+
+        for (int u : top) {
+            if (k <= 1) break;
+
+            if (vis[u]) continue;
+
+            for (int v : g[u]) {
+                if (vis[v]) continue;
+
+                vis[u] = vis[v] = true;
+                ans++;
+                k -= 2;
+            }
+        }
+
+        cout << ans + k << endl;
+    }
+
+    return 0;
+}