Cod sursa(job #2615347)

Utilizator SleepyOverlordPatcas Csaba SleepyOverlord Data 14 mai 2020 14:00:55
Problema Flux maxim Scor 70
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 3.29 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, g, gt;
VI x, h, current1, current2;

void push(int u, int v, int kap)
{
	f[u][v] += kap;
	x[u] -= kap;
	x[v] += kap;
}

void relabel(int node)
{
	int mm = n * n;
	FORN(i, g[node].SZ)
	{
		int next = g[node][i];
		if (c[node][next] > f[node][next]) mm = min(mm, h[next]);
	}
	FORN(i, gt[node].SZ)
	{
		int next = gt[node][i];
		if (f[next][node] > 0) mm = min(mm, h[next]);
	}
	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);
	g.RS(n + 1);
	gt.RS(n + 1);
	current1.RS(n + 1);
	current2.RS(n + 1);
	FOR(i, 1, m)
	{
		int xx, yy, zz;
		cin >> xx >> yy >> zz;
		c[xx][yy] = zz;
		g[xx].PB(yy);
		gt[yy].PB(xx);
	}

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

	while (1)
	{
		VI nodes;
		FOR(i, 2, n - 1)
		{
			if (!x[i]) continue;
			if (!nodes.empty() && h[i] < h[nodes[0]]) nodes.CL;
			if (nodes.empty() || h[i] == h[nodes[0]]) nodes.PB(i);
		}
			
		if (nodes.empty()) break;
		FORN(j, nodes.SZ)
		{
			int node = nodes[j];
			while (x[node])
			{
				int i = current1[node];
				while (i < g[node].SZ)
				{
					int next = g[node][i];
					if (h[node] == (h[next] + 1))
					{
						if (c[node][next] > f[node][next]) 
						{
							int aux = min(x[node], c[node][next] - f[node][next]);
							push(node, next, aux);
							if (!x[node]) break;
						}
					}
					++i;
				}
				current1[node] = i;
				if (x[node])
				{
					i = current2[node];
					while (i < gt[node].SZ)
					{
						int next = gt[node][i];
						if (h[node] == (h[next] + 1))
						{
							if (f[next][node]) 
							{
								int aux = min(x[node], f[next][node]);
								push(next, node, -aux);
								if (!x[node]) break;
							}
						}
						++i;
					}
					current2[node] = i;
				}
					
				if (x[node]) 
				{
					relabel(node);
					current1[node] = 0;
					current2[node] = 0;
				}
			}
		}
	}

	cout << x[n];

	return 0;
}