UVALive-2197 Paint the Roads (fee stream)

The main topic: There are n points, M edge, your task is to select some of the edges, so that each selected edge of a number of non-public side of the loop, and each city happens in the K back road, the selected edge of the total weight required minimum

Problem-solving ideas: K loops, each city has, indicating that each city's degrees and degrees are K, so to build the edge
Source points to each city, capacity is K, cost 0
Each city is connected to a meeting point with a capacity of K and costs 0
Side connects two cities with a capacity of 1, the cost is the right value

Run minimum cost maximum flow

#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#include <vector>using namespace STD;#define N 1010#define INF 0x3f3f3f3fstructedge{intFrom, to, caps, flow, cost; Edge () {} Edge (intFromintTo,intCapintFlowintCost): From, to, Cap (CAP), flow, cost (cost) {}};structmcmf{intN, m, source, sink, flow, cost; vector<Edge>Edges vector<int>G[n];intD[n], F[n], p[n];BOOLVis[n];voidInitintN) { This->n = n; for(inti =0; I <= N;        i++) g[i].clear ();    Edges.clear (); }voidAddedge (intFromintTo,intCapintCost) {Edges.push_back (Edge (from, to, Cap,0, cost)); Edges.push_back (Edge (to, from,0,0,-cost));        m = Edges.size (); G[from].push_back (M-2); G[to].push_back (M-1); }BOOLBellmanford (intSintTint&flow,int&cost) { for(inti =0; I <= N; i++) D[i] = INF;memset(Vis,0,sizeof(VIS)); Vis[s] =1; D[s] =0; F[s] = INF; P[s] =0; Queue<int>Q; Q.push (s); while(! Q.empty ()) {intU = Q.front ();            Q.pop (); Vis[u] =0; for(inti =0; I < g[u].size (); i++) {Edge &e = edges[g[u][i]];if(E.cap > E.flow && d[e.to] > D[u] + e.cost)                    {D[e.to] = D[u] + e.cost;                    P[e.to] = G[u][i]; F[e.to] = min (F[u], e.cap-e.flow);if(!vis[e.to]) {Vis[e.to] =true;                    Q.push (e.to); }                }            }        }if(D[t] = = INF)return false;        Flow + = F[t]; Cost + = D[t];intu = t; while(U! = s)            {Edges[p[u]].flow + = f[t]; Edges[p[u] ^1].flow-= f[t];        u = edges[p[u]].from; }return true; }voidMincost (intSintT) {flow =0, cost =0; while(Bellmanford (S, t, flow, cost)); }}; MCMF MCMF;intN, M, K;voidSolve () {scanf("%d%d%d", &n, &m, &k);intSource =2* N, sink =2* n +1; Mcmf.init (sink); for(inti =0; I < n; i++) {MCMF. Addedge (Source, I *2K0); MCMF. Addedge (i *2+1, Sink, K,0); }intU, V, c; for(inti =1; I <= m; i++) {scanf("%d%d%d", &u, &v, &c); MCMF. Addedge (U *2, V *2+1,1, c); } MCMF. Mincost (source, sink);if(Mcmf.flow = = k * N)printf("%d\n", mcmf.cost);Else printf(" -1\n");}intMain () {intTestscanf("%d", &test); while(test--) solve ();return 0;}

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UVALive-2197 Paint the Roads (fee stream)