HDU-4280 Island Transport (ISAP)

Ask you to send visitors from the east to the west, anyway the side is two-way, no difference

Problem-solving ideas: bare stream

ISAP 8080MS

#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#include <queue>using namespace STD;#define N 100010#define INF 0x3f3f3f3fstructEdge {intFrom, to, cap, flow; Edge () {} Edge (intFromintTo,intCapintFlow): From, to, Cap (CAP), flow (flow) {}};structISAP {intP[n], Num[n], cur[n], d[n];intT, S, N, M;BOOLVis[n]; vector<int>G[n]; vector<Edge>EdgesvoidInitintN) { This->n = n; for(inti =0; I <= N;            i++) {g[i].clear ();        D[i] = INF;    } edges.clear (); }voidAddedge (intFromintTo,intCAP) {Edges.push_back (Edge (from, to, Cap,0)); Edges.push_back (Edge (to, from,0,0));        m = Edges.size (); G[from].push_back (M-2); G[to].push_back (M-1); }BOOLBFS () {memset(Vis,0,sizeof(VIS)); Queue<int>Q; D[T] =0; VIS[T] =1; Q.push (t); while(! Q.empty ()) {intU = Q.front (); Q.pop (); for(inti =0; I < g[u].size (); i++) {Edge &e = edges[g[u][i] ^1];if(!vis[e.from] && e.cap > E.flow) {Vis[e.from] =true; D[e.from] = D[u] +1;                Q.push (E.from); }            }        }returnVis[s]; }intAugment () {intU = T, flow = INF; while(U! = s)            {Edge &e = edges[p[u]];            flow = min (flow, e.cap-e.flow);        u = edges[p[u]].from; } u = t; while(U! = s)            {Edges[p[u]].flow + = flow; Edges[p[u] ^1].flow-= flow;        u = edges[p[u]].from; }returnFlow }intMaxflow (intSintT) { This->s = s; This->t = t;intFlow =0; BFS ();if(D[s] >= N)return 0;memset(Num,0,sizeof(num));memset(cur,0,sizeof(cur)); for(inti =0; I < n; i++)if(D[i] < INF) num[d[i]]++;intU = s; while(D[s] < n) {if(U = = t)                {Flow + = Augment ();            U = s; }BOOLOK =false; for(inti = Cur[u]; I < g[u].size (); i++) {Edge &e = edges[g[u][i]];if(E.cap > E.flow && d[u] = = D[e.to] +1) {OK =true;                     P[e.to] = G[u][i];                    Cur[u] = i; u = e.to; Break; }            }if(!ok) {intMin = N-1; for(inti =0; I < g[u].size (); i++) {Edge &e = edges[g[u][i]];if(E.cap > E.flow)                min = min (min, d[e.to]); }if(--num[d[u]] = =0) Break; Num[d[u] = Min +1]++; Cur[u] =0;if(U! = s) u = edges[p[u]].from; }        }returnFlow }};isap ISAP;intN, M;voidInit () {scanf("%d%d", &n, &m); Isap.init (n);intx, y;intMin = INF, Max =-inf;intS, t; for(inti =1; I <= N; i++) {scanf("%d%d", &x, &y);if(x <= Min)            {s = i;        Min = x; }if(x >= Max)            {T = i;        Max = x; }    }intU, V, c; for(inti =0; I < m; i++) {scanf("%d%d%d", &u, &v, &c); Isap.        Addedge (U, V, c); Isap.    Addedge (V, U, c); }intAns = isap. Maxflow (S, t);printf("%d\n", ans);}intMain () {intTestscanf("%d", &test); while(test--)    {init (); }return 0;}

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HDU-4280 Island Transport (ISAP)