Ultraviolet A 12125-March of the Penguins (maximum Stream)

Ultraviolet A 12125-March of the Penguins

Question Link

Given some ice cubes, each ice cube has some penguins. Each ice cube has a limit on the number of jumps. Each Ice Cube is in a coordinate. Now, every penguin jumps to D, ask all penguins if they can jump to a point. If they can output all the frozen ice cubes, print-1 if there is no solution.

Idea: Maximum stream. Split points indicate the limit on the number of ice cubes, and then enumerate the blocks to create the largest stream.

Code:

#include <cstdio>#include <cstring>#include <queue>#include <algorithm>#include <cmath>using namespace std;const int MAXNODE = 105 * 2;const int MAXEDGE = 200005;typedef int Type;const Type INF = 0x3f3f3f3f;struct Edge {int u, v;Type cap, flow;Edge() {}Edge(int u, int v, Type cap, Type flow) {this->u = u;this->v = v;this->cap = cap;this->flow = flow;}};struct Dinic {int n, m, s, t;Edge edges[MAXEDGE];int first[MAXNODE];int next[MAXEDGE];bool vis[MAXNODE];Type d[MAXNODE];int cur[MAXNODE];vector<int> cut;void init(int n) {this->n = n;memset(first, -1, sizeof(first));m = 0;}void add_Edge(int u, int v, Type cap) {edges[m] = Edge(u, v, cap, 0);next[m] = first[u];first[u] = m++;edges[m] = Edge(v, u, 0, 0);next[m] = first[v];first[v] = m++;}bool bfs() {memset(vis, false, sizeof(vis));queue<int> Q;Q.push(s);d[s] = 0;vis[s] = true;while (!Q.empty()) {int u = Q.front(); Q.pop();for (int i = first[u]; i != -1; i = next[i]) {Edge& e = edges[i];if (!vis[e.v] && e.cap > e.flow) {vis[e.v] = true;d[e.v] = d[u] + 1;Q.push(e.v);}}}return vis[t];}Type dfs(int u, Type a) {if (u == t || a == 0) return a;Type flow = 0, f;for (int &i = cur[u]; i != -1; i = next[i]) {Edge& e = edges[i];if (d[u] + 1 == d[e.v] && (f = dfs(e.v, min(a, e.cap - e.flow))) > 0) {e.flow += f;edges[i^1].flow -= f;flow += f;a -= f;if (a == 0) break;}}return flow;}bool Maxflow(int s, int t, int tot) {this->s = s; this->t = t;Type flow = 0;while (bfs()) {for (int i = 0; i < n; i++)cur[i] = first[i];flow += dfs(s, INF);}return flow == tot;}void MinCut() {cut.clear();for (int i = 0; i < m; i += 2) {if (vis[edges[i].u] && !vis[edges[i].v])cut.push_back(i);}}} gao;const int N = 105;int t, n;double d;struct Point {int x, y, n, m;void read() {scanf("%d%d%d%d", &x, &y, &n, &m);}} p[N];double dis(Point a, Point b) {int dx = a.x - b.x;int dy = a.y - b.y;return sqrt(dx * dx * 1.0 + dy * dy);}int tot;bool solve(int u) {gao.init(2 * n + 2);for (int i = 1; i <= n; i++)gao.add_Edge(0, i, p[i].n);gao.add_Edge(u + n, 2 * n + 1, tot);for (int i = 1; i <= n; i++) {if (i == u) gao.add_Edge(i, i + n, tot);else gao.add_Edge(i, i + n, p[i].m);for (int j = i + 1; j <= n; j++) {if (dis(p[i], p[j]) > d) continue;gao.add_Edge(i + n, j, tot);gao.add_Edge(j + n, i, tot);}}return gao.Maxflow(0, 2 * n + 1, tot);}int main() {scanf("%d", &t);while (t--) {scanf("%d%lf", &n, &d);tot = 0;for (int i = 1; i <= n; i++) {p[i].read();tot += p[i].n;}int bo = 0;for (int i = 1; i <= n; i++) {if (!solve(i)) continue;if (bo) printf(" ");else bo = 1;printf("%d", i - 1);}if (bo == 0) printf("-1");printf("\n");}return 0;}

Ultraviolet A 12125-March of the Penguins (maximum Stream)