#1494. 导弹拦截

https://sjzezoj.com/submission/55732

S2OJ/1494/1494.cpp

@@ -0,0 +1,134 @@
+#include <iostream>
+#include <algorithm>
+#include <limits>
+#include <queue>
+#include <tuple>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e6 + 5;
+
+int n, s, t, f[N], ans;
+std::tuple<int, int, int> points[N];
+int idx, head[N << 1], ver[N << 2], edge[N << 2], next[N << 2];
+int cur[N << 1], dist[N << 1];
+
+void add(int u, int v, int w) {
+    next[idx] = head[u];
+    ver[idx] = v;
+    edge[idx] = w;
+    head[u] = idx++;
+}
+
+bool bfs() {
+    std::fill_n(dist, N << 1, 0);
+
+    std::queue<int> q;
+
+    q.push(s);
+    dist[s] = 1;
+    cur[s] = head[s];
+
+    while (!q.empty()) {
+        int u = q.front();
+        q.pop();
+
+        for (int i = head[u]; ~i; i = next[i]) {
+            int v = ver[i],
+                w = edge[i];
+
+            if (w && !dist[v]) {
+                dist[v] = dist[u] + 1;
+                cur[v] = head[v];
+                if (v == t) return true;
+                q.push(v);
+            }
+        }
+    }
+    return false;
+}
+
+int dinic(int u, int limit) {
+    if (u == t) return limit;
+
+    int flow = 0;
+
+    for (int i = cur[u]; ~i && flow < limit; i = next[i]) {
+        cur[u] = i;
+
+        int v = ver[i],
+            w = edge[i];
+
+        if (dist[v] == dist[u] + 1 && w) {
+            int k = dinic(v, std::min(w, limit - flow));
+
+            if (!k) {
+                dist[v] = 0;
+            } else {
+                flow += k;
+                edge[i] -= k;
+                edge[i ^ 1] += k;
+            }
+        }
+    }
+
+    return flow;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    std::fill_n(head, N << 1, -1);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> std::get<0>(points[i]) >> std::get<1>(points[i]) >> std::get<2>(points[i]);
+    }
+
+    std::sort(points + 1, points + 1 + n);
+
+    for (int i = 1; i <= n; i++) {
+        f[i] = 1;
+
+        for (int j = 1; j < i; j++) {
+            int x1, y1, z1,
+                x2, y2, z2;
+
+            std::tie(x1, y1, z1) = points[i];
+            std::tie(x2, y2, z2) = points[j];
+
+            if (x2 < x1 && y2 < y1 && z2 < z1) {
+                f[i] = std::max(f[i], f[j] + 1);
+
+                add(j, i + n, 1);
+                add(i + n, j, 0);
+            }
+        }
+
+        ans = std::max(ans, f[i]);
+    }
+
+    s = n * 2 + 1, t = s + 1;
+    for (int i = 1; i <= n; i++) {
+        add(s, i, 1);
+        add(i, s, 0);
+
+        add(i + n, t, 1);
+        add(t, i + n, 0);
+    }
+
+    int res = 0, flow;
+    while (bfs()) {
+        while (flow = dinic(s, std::numeric_limits<int>::max())) res += flow;
+    }
+
+    cout << ans << endl
+         << n - res << endl;
+
+    return 0;
+}

S2OJ/1496/1496.cpp

@@ -0,0 +1,106 @@
+#include <iostream>
+#include <algorithm>
+#include <string>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 15;
+
+int n, t, a[N << 2], b[N << 2];
+
+bool check() {
+    int cnt = 0;
+
+    for (int i = 1; i <= 27; i++) {
+        if (b[i] < 0) return false;
+        if (b[i] >= 3) {
+            b[i] -= 3;
+            cnt++;
+        }
+
+        if (i % 9 == 0 || i % 9 == 8) continue;
+
+        while (b[i] > 0) {
+            b[i]--, b[i + 1]--, b[i + 2]--;
+            cnt++;
+        }
+    }
+
+    return cnt == 4;
+}
+
+bool check_hu() {
+    bool flag = false;
+
+    for (int i = 1; i <= 27; i++) {
+        if (a[i] >= 2) flag = true;
+    }
+
+    if (!flag) return false;
+
+    for (int i = 1; i <= 27; i++) {
+        if (a[i] < 2) continue;
+
+        std::copy_n(a, N << 2, b);
+        b[i] -= 2;
+
+        if (check()) return true;
+    }
+
+    return false;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> t;
+
+    while (t--) {
+        std::fill_n(a, N << 2, 0);
+
+        for (int i = 1; i <= n; i++) {
+            std::string s;
+
+            cin >> s;
+
+            int x = s[0] - '0';
+            char c = s[1];
+
+            if (c == 'p') x += 9;
+            else if (c == 's') x += 18;
+
+            a[x]++;
+        }
+
+        if (n == 14) {
+            cout << check_hu() << endl;
+        } else {  // n == 13
+            for (int i = 1; i <= 27; i++) {
+                if (a[i] < 4) {
+                    a[i]++;
+
+                    if (check_hu()) {
+                        cout << (i - 1) % 9 + 1;
+
+                        if (1 <= i && i <= 9) {
+                            cout << "m ";
+                        } else if (10 <= i && i <= 18) {
+                            cout << "p ";
+                        } else {  // 19 <= i && i <= 27
+                            cout << "s ";
+                        }
+                    }
+
+                    a[i]--;
+                }
+            }
+
+            cout << endl;
+        }
+    }
+
+    return 0;
+}

utils/graph.h

@@ -0,0 +1,37 @@
+#include <tuple>
+#include <vector>
+
+template <typename T>
+class Graph {
+  private:
+    // Indexes of the first edge of each vertex.
+    std::vector<std::size_t> head;
+
+    // Edges of the graph.
+    // Elements in a std::tuple are <to, weight, next>
+    std::vector<std::tuple<std::size_t, T, std::size_t>> edge;
+
+  public:
+    Graph() = default;
+
+    Graph(const int &_n)
+        : head(n, -1) {}
+
+    // Add an edge from u to v with weight w.
+    void add(const std::size_t &_u, const std::size_t &_v, const T &_w) {
+        edge.emplace_back(_v, _w, head[_u]);
+        head[_u] = edge.size() - 1;
+    }
+
+    // Add an undirected edge from u to v with weight `w`.
+    void add_undirected(const std::size_t &_u, const std::size_t &_v, const T &_w) {
+        add(_u, _v, _w);
+        add(_v, _u, _w);
+    }
+
+    // Add an undirected edge from u to v with weight `w`, specifies the weight `rw` of reverse edge.
+    void add_undirected(const std::size_t &_u, const std::size_t &_v, const T &_w, const T &_rw) {
+        add(_u, _v, _w);
+        add(_v, _u, _rw);
+    }
+};