Cod sursa(job #2615252)

Utilizator SleepyOverlordPatcas Csaba SleepyOverlord Data 13 mai 2020 22:33:48
Problema Flux maxim Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 2.52 kb
#include <vector>
#include <string> 
#include <set> 
#include <map> 
#include <queue> 
#include <bitset> 
#include <stack>
#include <list>

#include <numeric> 
#include <algorithm> 

#include <cstdio>
#include <fstream>
#include <iostream> 
#include <sstream> 
#include <iomanip>

#include <cctype>
#include <cmath> 
#include <ctime>
#include <cassert>

using namespace std;

#define LL long long
#define PII pair <int, int>
#define VB vector <bool>
#define VI vector <int>
#define VD vector <double>
#define VS vector <string>
#define VPII vector <pair <int, int> >
#define VVI vector < VI >
#define VVB vector < VB >

#define FORN(i, n) for(int i = 0; i < (n); ++i)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define FORI(it, X) for(__typeof((X).begin()) it = (X).begin(); it !=(X).end(); ++it) 
#define REPEAT do{ 
#define UNTIL(x) }while(!(x)); 

#define SZ size()
#define BG begin() 
#define EN end() 
#define CL clear()
#define X first
#define Y second
#define RS resize
#define PB push_back
#define MP make_pair
#define ALL(x) x.begin(), x.end()

#define IN_FILE "maxflow.in"
#define OUT_FILE "maxflow.out"

int n, m;
VVI c, f;
queue<int> fifo;
VI x, h;

void push(int u, int v, int kap)
{
	if (x[v] == 0 && kap > 0) fifo.push(v);
	else 
		if (x[u] == 0 && kap < 0) fifo.push(u);
	f[u][v] += kap;
	x[u] -= kap;
	x[v] += kap;
}

void relabel(int node)
{
	int mm = n * n;
	FOR(i, 1, n)
		if ((c[node][i] > f[node][i]) || (f[i][node] > 0)) mm = min(mm, h[i]);
	h[node] = mm + 1;
}

int main()
{
	freopen(IN_FILE, "r", stdin);
	freopen(OUT_FILE, "w", stdout);

	cin >> n >> m;
	c.RS(n + 1, VI(n + 1));
	f.RS(n + 1, VI(n + 1));
	x.RS(n + 1);
	h.RS(n + 1);
	FOR(i, 1, m)
	{
		int xx, yy, zz;
		cin >> xx >> yy >> zz;
		c[xx][yy] = zz;
	}

	h[1] = n;
	FOR(i, 1, n) 
	{
		f[1][i] = c[1][i];
		x[i] += f[1][i];
		if (f[1][i]) fifo.push(i);
	}

	while (!fifo.empty())
	{
		int node = fifo.front();
		fifo.pop();
		if (node == n || node == 1) continue;
		while (x[node])
		{
			FOR(i, 1, n)
				if (h[node] == (h[i] + 1))
				{
					if (c[node][i] > f[node][i]) 
					{
						int aux = min(x[node], c[node][i] - f[node][i]);
						push(node, i, aux);
						if (!x[node]) break;
					}
					if (f[i][node]) 
					{
						int aux = min(x[node], f[i][node]);
						push(i, node, -aux);
						if (!x[node]) break;
					}
				}
			if (x[node]) relabel(node);
		}
	}

	cout << x[n];

	return 0;
}