Cod sursa(job #2696521)

Utilizator alex2209alexPavel Alexandru alex2209alex Data 16 ianuarie 2021 09:36:49
Problema Flux maxim Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.11 kb
#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 f("maxflow.in");
ofstream g("maxflow.out");
//--------------------------------
///Globale
const int NMAX = 1001;
int n,cap[NMAX][NMAX],flow[NMAX][NMAX],coada[NMAX],par[NMAX],rasp;
bitset<NMAX>ap;
vector<int>muchii[NMAX];
//--------------------------------
///Functii
void citire();
void rezolvare();
void afisare();
//--------------------------------
int main()
{
	citire();
	rezolvare();
	afisare();
}
//--------------------------------
void afisare()
{
	g << rasp;
}
//--------------------------------
bool bfs()
{
	int nr = 1;
	coada[1] = 1;
	int i = 1;
	ap = {0};
	ap[1] = 1;
	while(i <= nr)
	{
		int nod = coada[i];
		if(nod == n)
			return 1;
		i++;
		for(auto it : muchii[nod])
            if(ap[it] == 0 && flow[nod][it] < cap[nod][it])
			{
				ap[it] = 1;
				nr++;
				coada[nr] = it;
				par[it] = nod;
			}
	}
	return 0;
}
//--------------------------------
void rezolvare()
{
	while(bfs())
	{
		int nod = n;
		int fl = 200000;
		while(par[nod] != 0)
		{
			int x = par[nod];
			if(fl > cap[x][nod] - flow[x][nod])
				fl = cap[x][nod] - flow[x][nod];
			nod = x;
		}
		nod = n;
		while(par[nod] != 0)
		{
			int x = par[nod];
			flow[x][nod] += fl;
			flow[nod][x] -= fl;
			nod = x;
		}
		rasp += fl;
	}
}
//--------------------------------
void citire()
{
	int m;
	f >> n >> m;
	while(m--)
	{
		int x,y,c;
		f >> x >> y >> c;
		muchii[x].push_back(y);
		cap[x][y] += c;
		muchii[y].push_back(x);
	}
}