Pagini recente » Cod sursa (job #975998) | Cod sursa (job #2872163) | Cod sursa (job #1978454) | Cod sursa (job #2553960) | Cod sursa (job #2730686)
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream fin("traseu.in");
ofstream fout("traseu.out");
const int N = 65;
const int INF = 1e9;
int n, m, fmax, costMin, gn;
int t[N], cap[N][N], cost[N][N], flow[N][N], gradInt[N], gradExt[N];
vector<int> dist;
vector<int> g[N];
vector<bool> vis;
vector<bool> inCoada;
void BellmanFordCoada(int startNode)
{
inCoada.assign(gn, false);
dist.assign(gn, INF);
queue<int> coada;
coada.push(startNode);
inCoada[startNode] = true;
dist[startNode] = 0;
t[startNode] = 0;
while(!coada.empty())
{
int x = coada.front();
coada.pop();
inCoada[x] = false;
for (int y : g[x])
{
if (dist[x] + cost[x][y] < dist[y] && flow[x][y] != cap[x][y])
{
t[y] = x;
dist[y] = dist[x] + cost[x][y];
if (!inCoada[y])
{
coada.push(y);
inCoada[y] = true;
}
}
}
}
}
void maxFlowMinCost(int source, int sink)
{
do
{
BellmanFordCoada(source);
if(dist[sink] == INF)
break;
int fmin = 1 << 30;
for(int node = sink; node != source; node = t[node])
fmin = min(fmin, cap[t[node]][node] - flow[t[node]][node]);
fmax += fmin;
costMin += dist[sink] * fmin;
for(int node = sink; node != source; node = t[node])
{
flow[t[node]][node] += fmin;
flow[node][t[node]] -= fmin;
}
} while(dist[sink] != INF);
}
void addEdge(int x, int y, int c, int z)
{
g[x].push_back(y);
g[y].push_back(x);
cap[x][y] = c;
cap[y][x] = 0;
cost[x][y] = z;
cost[y][x] = -z;
}
int main()
{
fin >> n >> m;
gn = n + 2;
int ans = 0;
for (int i = 1; i <= m; i++)
{
int x, y, c;
fin >> x >> y >> c;
ans += c;
addEdge(x, y, INF, c);
gradExt[x]++;
gradInt[y]++;
}
for (int i = 1; i <= n; i++)
{
if (gradInt[i] > gradExt[i])
addEdge(0, i, gradInt[i] - gradExt[i], 0);
else if (gradInt[i] < gradExt[i])
addEdge(i, n + 1, gradExt[i] - gradInt[i], 0);
}
maxFlowMinCost(0, n + 1);
fout << ans + costMin << '\n';
return 0;
}