Cod sursa(job #2600678)

Utilizator alex2209alexPavel Alexandru alex2209alex Data 13 aprilie 2020 07:21:15
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.54 kb
#include <fstream>
#include <bits/stdc++.h>
using namespace std;
class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
};
InParser f("maxflow.in");
ofstream g("maxflow.out");
vector<long long> G[2001];
long long n,m,i,x,y,z,flow,TT[2001],F[2001][2001],C[2001][2001],viz[2001],cd[2001],rasp,flowmin,nod;
long long BF()
{
    int i, j, nod, V;
    cd[0]=1;
    cd[1]=1;
    memset(viz,0,sizeof(viz));
    viz[1]=1;
    for (i=1; i<=cd[0]; i++)
    {
        nod=cd[i];
        if(nod==n)
        {
            continue;
        }
        for(j=0; j<G[nod].size(); j++)
        {
            V=G[nod][j];
            if(C[nod][V]==F[nod][V]||viz[V])
            {
                continue;
            }
            viz[V]=1;
            cd[++cd[0]]=V;
            TT[V]=nod;
        }
    }
    return viz[n];
}
int main()
{
    f>>n>>m;
    for (i=1; i<=m; i++)
    {
        f>>x>>y>>z;
        C[x][y]+=z;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    for (flow=0; BF();)
    {
        for (i=0;i<G[n].size();i++)
        {
            nod=G[n][i];
            if (F[nod][n]==C[nod][n]||!viz[nod])
            {
                continue;
            }
            TT[n]=nod;
            flowmin=100000000009;
            for(nod=n;nod!=1;nod=TT[nod])
            {
                flowmin=min(flowmin,C[TT[nod]][nod]-F[TT[nod]][nod]);
            }
            if(flowmin==0)
            {
                continue;
            }
            for(nod=n;nod!=1; nod=TT[nod])
            {
                F[TT[nod]][nod]+=flowmin;
                F[nod][TT[nod]]-=flowmin;
            }
            flow+=flowmin;
        }
    }
    g<<flow;
    return 0;
}