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// Copied from https://gist.github.com/Chillee/ad2110fc17af453fb6fc3357a78cfd28 // // More about it in https://codeforces.com/blog/entry/66006 // // Notes: // - large arrays in struct. Do not put MaxFlow variable in main // - cannot recover flow // // Tested: // - https://oj.vnoi.info/problem/fflow // - https://www.spoj.com/problems/FASTFLOW/ // - https://loj.ac/p/127 // MaxFlow {{{ template <int MAXN, class T = int> struct MaxFlow { MaxFlow() {} const T INF = numeric_limits<T>::max(); struct edge { int to, rev; T f; }; int t = -1; vector<edge> adj[MAXN]; vector<int> lst[MAXN], gap[MAXN]; T excess[MAXN]; int highest, height[MAXN], cnt[MAXN], work; void addEdge(int from, int to, int f, bool isDirected = true) { adj[from].push_back({to, (int)adj[to].size(), f}); adj[to].push_back({from, ((int)adj[from].size()) - 1, isDirected ? 0 : f}); } void updHeight(int v, int nh) { work++; if (height[v] != MAXN) cnt[height[v]]--; height[v] = nh; if (nh == MAXN) return; cnt[nh]++, highest = nh; gap[nh].push_back(v); if (excess[v] > 0) lst[nh].push_back(v); } void globalRelabel() { work = 0; fill(height, height + MAXN, MAXN); fill(cnt, cnt + MAXN, 0); for (int i = 0; i < highest; i++) lst[i].clear(), gap[i].clear(); height[t] = 0; queue<int> q({t}); while (!q.empty()) { int v = q.front(); q.pop(); for (auto &e : adj[v]) if (height[e.to] == MAXN && adj[e.to][e.rev].f > 0) q.push(e.to), updHeight(e.to, height[v] + 1); highest = height[v]; } } void push(int v, edge &e) { if (excess[e.to] == 0) lst[height[e.to]].push_back(e.to); T df = min(excess[v], e.f); e.f -= df, adj[e.to][e.rev].f += df; excess[v] -= df, excess[e.to] += df; } void discharge(int v) { int nh = MAXN; for (auto &e : adj[v]) { if (e.f > 0) { if (height[v] == height[e.to] + 1) { push(v, e); if (excess[v] <= 0) return; } else nh = min(nh, height[e.to] + 1); } } if (cnt[height[v]] > 1) updHeight(v, nh); else { for (int i = height[v]; i <= highest; i++) { for (auto j : gap[i]) updHeight(j, MAXN); gap[i].clear(); } } } T getMaxFlow(int s, int _t, int heur_n = MAXN) { t = _t; assert(s >= 0 && t >= 0); fill(begin(excess), end(excess), 0); excess[s] = INF, excess[t] = -INF; globalRelabel(); for (auto &e : adj[s]) push(s, e); for (; highest >= 0; highest--) { while (!lst[highest].empty()) { int v = lst[highest].back(); lst[highest].pop_back(); discharge(v); if (work > 4 * heur_n) globalRelabel(); } } return excess[t] + INF; } }; // }}}
#line 1 "Graph/MaxFlow/MaxFlowHLPP.h" // Copied from https://gist.github.com/Chillee/ad2110fc17af453fb6fc3357a78cfd28 // // More about it in https://codeforces.com/blog/entry/66006 // // Notes: // - large arrays in struct. Do not put MaxFlow variable in main // - cannot recover flow // // Tested: // - https://oj.vnoi.info/problem/fflow // - https://www.spoj.com/problems/FASTFLOW/ // - https://loj.ac/p/127 // MaxFlow {{{ template <int MAXN, class T = int> struct MaxFlow { MaxFlow() {} const T INF = numeric_limits<T>::max(); struct edge { int to, rev; T f; }; int t = -1; vector<edge> adj[MAXN]; vector<int> lst[MAXN], gap[MAXN]; T excess[MAXN]; int highest, height[MAXN], cnt[MAXN], work; void addEdge(int from, int to, int f, bool isDirected = true) { adj[from].push_back({to, (int)adj[to].size(), f}); adj[to].push_back({from, ((int)adj[from].size()) - 1, isDirected ? 0 : f}); } void updHeight(int v, int nh) { work++; if (height[v] != MAXN) cnt[height[v]]--; height[v] = nh; if (nh == MAXN) return; cnt[nh]++, highest = nh; gap[nh].push_back(v); if (excess[v] > 0) lst[nh].push_back(v); } void globalRelabel() { work = 0; fill(height, height + MAXN, MAXN); fill(cnt, cnt + MAXN, 0); for (int i = 0; i < highest; i++) lst[i].clear(), gap[i].clear(); height[t] = 0; queue<int> q({t}); while (!q.empty()) { int v = q.front(); q.pop(); for (auto &e : adj[v]) if (height[e.to] == MAXN && adj[e.to][e.rev].f > 0) q.push(e.to), updHeight(e.to, height[v] + 1); highest = height[v]; } } void push(int v, edge &e) { if (excess[e.to] == 0) lst[height[e.to]].push_back(e.to); T df = min(excess[v], e.f); e.f -= df, adj[e.to][e.rev].f += df; excess[v] -= df, excess[e.to] += df; } void discharge(int v) { int nh = MAXN; for (auto &e : adj[v]) { if (e.f > 0) { if (height[v] == height[e.to] + 1) { push(v, e); if (excess[v] <= 0) return; } else nh = min(nh, height[e.to] + 1); } } if (cnt[height[v]] > 1) updHeight(v, nh); else { for (int i = height[v]; i <= highest; i++) { for (auto j : gap[i]) updHeight(j, MAXN); gap[i].clear(); } } } T getMaxFlow(int s, int _t, int heur_n = MAXN) { t = _t; assert(s >= 0 && t >= 0); fill(begin(excess), end(excess), 0); excess[s] = INF, excess[t] = -INF; globalRelabel(); for (auto &e : adj[s]) push(s, e); for (; highest >= 0; highest--) { while (!lst[highest].empty()) { int v = lst[highest].back(); lst[highest].pop_back(); discharge(v); if (work > 4 * heur_n) globalRelabel(); } } return excess[t] + INF; } }; // }}}