Bzoj 1570 Jsoi Travel Network flow of Blue Mary

Main topic

Given a graph, each person can only do once a day plane. Now give the starting point, the end point, and the number of people to go, as well as the number of restrictions on each route, and ask at least how many days the slowest person reaches the finish line.

Ideas

is obviously the network flow model, as to how to verify, in fact, even two points are not used, enumerate the minimum number of days, and then each add a layer of edge to verify on the line.

CODE

#define _crt_secure_no_warnings#include <queue>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#define MAX 100010#define Maxe 1000010#define S 0#define SS (MAX-2)#define T (MAX-1)#define INF 0x3f3f3f3fusing namespace STD;structedge{intX, y, Z;voidRead () {scanf("%d%d%d", &x, &y, &z); }}edge[maxe];structmaxflow{intHead[max], total;int_next[maxe], Aim[maxe], flow[maxe];intBackup_flow[maxe];intDeep[maxe]; Maxflow (): Total (1) {}voidADD (intXintYintf) {_next[++total] = head[x];        Aim[total] = y;        Backup_flow[total] = f;    HEAD[X] = total; }voidInsert (intXintYintf) {Add (x, Y, F); Add (y, X,0); }BOOLBFS () {Static  Queue<int>Q while(!q.empty ()) Q.pop ();memset(Deep,0,sizeof(deep)); Deep[s] =1; Q.push (S); while(!q.empty ()) {intx = Q.front (); Q.pop (); for(inti = head[x]; I i = _next[i])if(Flow[i] &&!deep[aim[i]) {Deep[aim[i]] = deep[x] +1; Q.push (Aim[i]);if(Aim[i] = = T)return true; }        }return false; }intDinic (intXintf) {if(x = = T)returnFinttemp = f; for(inti = head[x]; I i = _next[i])if(Flow[i] && temp && deep[aim[i]] = = Deep[x] +1) {intaway = Dinic (Aim[i], min (flow[i], temp));if(!away) deep[aim[i]] =0;            Flow[i]-= away; Flow[i ^1] + = away;        Temp-= away; }returnF-temp; }}solver;intPoints, edges, persons;intMain () {Cin>> points >> edges >> persons; for(inti =1; I <= edges; ++i) Edge[i].    Read (); Solver. Insert (S, SS, persons);intnow =0; for(inti =1;; ++i) { for(intj =1; J <= Edges; ++J) Solver.        Insert (now + edge[j].x, now + edge[j].y + points, edge[j].z); Solver.        Insert (now + points + points, T, INF); Solver. Insert (SS, now +1, INF);memcpy(Solver.flow, Solver.backup_flow,sizeof(Solver.flow));intMax_flow =0; while(Solver. BFS ()) Max_flow + = Solver. Dinic (S, INF);if(Max_flow = = persons) {cout<< i << Endl;return 0;    } now + = points; }return 0;}

Bzoj 1570 Jsoi Travel Network flow of Blue Mary