#1810. 【2017.3 长乐省选集训 Day5 T3】炮塔

https://sjzezoj.com/submission/66316

S2OJ/1810/1810.cpp

@@ -0,0 +1,167 @@
+#include <iostream>
+#include <algorithm>
+#include <iterator>
+#include <queue>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 55 * 55 * 2,
+          M = N * N;
+const int INF = 0x3f3f3f3f;
+
+int n, m, s, t, a[55][55], flow, res, ans;
+int idx, head[N], ver[M << 1], edge[M << 1], next[M << 1];
+int dis[N], cur[N];
+
+int id(int x, int y, int k) {
+    return k * n * m + x * m + y;
+}
+
+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(std::begin(dis), std::end(dis), 0);
+
+    std::queue<int> q;
+
+    q.emplace(s);
+    dis[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 && !dis[v]) {
+                dis[v] = dis[u] + 1;
+                cur[v] = head[v];
+
+                if (v == t) return true;
+
+                q.emplace(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 (w && dis[v] == dis[u] + 1) {
+            int k = dinic(v, std::min(w, limit - flow));
+
+            if (!k) dis[v] = 0;
+
+            edge[i] -= k;
+            edge[i ^ 1] += k;
+            flow += k;
+        }
+    }
+
+    return flow;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    s = 0, t = id(n, m, 1) + 1;
+    std::fill(std::begin(head), std::end(head), -1);
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= m; j++) {
+            cin >> a[i][j];
+
+            add(id(i, j, 0), id(i, j, 1), INF);
+            add(id(i, j, 1), id(i, j, 0), 0);
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= m; j++) {
+            int max = 0;
+
+            if (a[i][j] == -1) {
+                add(s, id(i, j, 0), INF);
+                add(id(i, j, 0), s, 0);
+
+                for (int k = i; k >= 1; k--) {
+                    max = std::max(max, a[k][j]);
+                }
+
+                for (int k = i; k > 1; k--) {
+                    add(id(k, j, 0), id(k - 1, j, 0), max - std::max(a[k][j], 0));
+                    add(id(k - 1, j, 0), id(k, j, 0), 0);
+                }
+            } else if (a[i][j] == -2) {
+                add(s, id(i, j, 0), INF);
+                add(id(i, j, 0), s, 0);
+
+                for (int k = i; k <= n; k++) {
+                    max = std::max(max, a[k][j]);
+                }
+
+                for (int k = i; k < n; k++) {
+                    add(id(k, j, 0), id(k + 1, j, 0), max - std::max(a[k][j], 0));
+                    add(id(k + 1, j, 0), id(k, j, 0), 0);
+                }
+            } else if (a[i][j] == -3) {
+                add(id(i, j, 1), t, INF);
+                add(t, id(i, j, 1), 0);
+
+                for (int k = 1; k <= j; k++) {
+                    max = std::max(max, a[i][k]);
+                }
+
+                for (int k = 1; k < j; k++) {
+                    add(id(i, k, 1), id(i, k + 1, 1), max - std::max(a[i][k + 1], 0));
+                    add(id(i, k + 1, 1), id(i, k, 1), 0);
+                }
+            } else if (a[i][j] == -4) {
+                add(id(i, j, 1), t, INF);
+                add(t, id(i, j, 1), 0);
+
+                for (int k = m; k >= j; k--) {
+                    max = std::max(max, a[i][k]);
+                }
+
+                for (int k = m; k > j; k--) {
+                    add(id(i, k, 1), id(i, k - 1, 1), max - std::max(a[i][k - 1], 0));
+                    add(id(i, k - 1, 1), id(i, k, 1), 0);
+                }
+            }
+
+            ans += max;
+        }
+    }
+
+    while (bfs()) {
+        while (flow = dinic(s, INF)) res += flow;
+    }
+
+    cout << ans - res << endl;
+
+    return 0;
+}