79 lines
1.9 KiB
C++
79 lines
1.9 KiB
C++
struct Edge
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{
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int to, cap, now;
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ll cost;
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Edge* rev;
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Edge(int to,int cap, ll cost)
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:to(to), cap(cap), now(0), cost(cost){}
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int left(){return cap - now;}
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ll flow(int f)
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{now += f; rev->now -= f; return cost * f;}
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void reset(){now = 0;}
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};
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vector<Edge*> adj[N];
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Edge* hist[N]; ll dist[N]; bool inQueue[N], chk[N];
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bool spfa(int s, int t)
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{
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memset(dist, 0, sizeof(dist));
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memset(chk, 0, sizeof(chk)); chk[s] = true;
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queue<int> q;
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memset(inQueue, 0, sizeof(inQueue));
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q.push(s); inQueue[s] = true;
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while(!q.empty())
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{
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int now = q.front();
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q.pop(); inQueue[now] = false;
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for(auto e : adj[now])
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{
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int next = e->to;
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if(e->left() > 0 and
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(chk[next] == false
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or dist[next] > dist[now] + e->cost))
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{
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chk[next] = true;
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dist[next] = dist[now] + e->cost;
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hist[next] = e;
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if(!inQueue[next])
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q.push(next), inQueue[next] = true;
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}
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}
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}
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return chk[t];
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}
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// cost가 들어가면 항상 단방향만 가능하다. (양방향 : 2번 connect)
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void connect(int from, int to, int cap, ll cost)
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{
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Edge *fw, *bw;
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fw = new Edge(to, cap, cost);
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bw = new Edge(from, 0, -cost);
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fw->rev = bw; bw->rev = fw;
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adj[from].push_back(fw);
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adj[to].push_back(bw);
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}
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//maximum matching & minimum cost
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pair<ll, ll> flow(int S,int T)
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{
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ll ans = 0; ll cost = 0;
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while(spfa(S, T))
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{
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int m = 2e9;
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int now = T;
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while(S != now)
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{
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m = min(m, hist[now]->left());
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now = hist[now]->rev->to;
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}
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now = T;
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while(S != now)
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{
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cost += hist[now]->flow(m);
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now = hist[now]->rev->to;
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}
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ans += m;
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}
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return {ans, cost};
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} |