Cod sursa(job #1878231)

Utilizator visanrVisan Radu visanr Data 13 februarie 2017 22:45:30
Problema Traseu Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 3.48 kb
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <vector>
#include <algorithm>
using namespace std;
 
 
const int nmax = 210;
const int inf = 0x3f3f3f3f;

struct Edge {
    int u, v, cap, flow, cost;
    Edge(int _u, int _v, int _cap, int _flow, int _cost) {
        u = _u;
        v = _v;
        cap = _cap;
        flow = _flow;
        cost = _cost;
    }
};

vector<Edge> E;
vector<int> g[nmax];
int n, m, degin[nmax], degout[nmax], cost[nmax][nmax], source, sink;
int father[nmax], dist[nmax];
bool inqueue[nmax];

bool bellmanford() {
    for (int i = source; i <= sink; ++ i) {
        inqueue[i] = 0;
        father[i] = -1;
        dist[i] = inf;
    }
    queue<int> q;
    q.push(source);
    dist[source] = 0;

    while (!q.empty()) {
        int node = q.front();
        q.pop();
        inqueue[node] = 0;
        for (int ind : g[node]) {
            Edge e = E[ind];
            if (e.cap > e.flow && dist[e.u] + e.cost < dist[e.v]) {
                dist[e.v] = dist[e.u] + e.cost;
                father[e.v] = ind;
                if (!inqueue[e.v]) {
                    inqueue[e.v] = 1;
                    q.push(e.v);
                }
            }
        }
    }
    return dist[sink] != inf;
}

int maxflow() {
    int ans = 0;
    while (bellmanford()) {
        int minflow = inf, node = sink;
        while (node != source) {
            Edge e = E[father[node]];
            minflow = min(minflow, e.cap - e.flow);
            node = e.u;
        }
        node = sink;
        while (node != source) {
            Edge &e = E[father[node]];
            Edge &re = E[father[node] ^ 1];

            e.flow += minflow;
            re.flow -= minflow;
            node = e.u;
        }
        ans += dist[sink] * minflow;
    }
    
    return ans;
}
  
void rf()
{
    for(int k = 1; k <= n; ++ k)
        for(int i = 1; i <= n; ++ i)
            for(int j = 1; j <= n; ++ j)
                if(i != k && j != k && cost[i][k] + cost[k][j] < cost[i][j])
                    cost[i][j] = cost[i][k] + cost[k][j];
}
 
int main()
{
    freopen("traseu.in", "r", stdin);
    freopen("traseu.out", "w", stdout);
    
    scanf("%i %i", &n, &m);
    for (int i = 1; i <= n; ++ i) {
        for (int j = 1; j <= n; ++ j) {
            cost[i][j] = inf;
        }
    }
    int ans = 0;

    for (int i = 1; i <= m; ++ i) {
        int x, y, c;
        scanf("%i %i %i", &x, &y, &c);
        ans += c;
        degout[x] ++;
        degin[y] ++;
        cost[x][y] = c;
    }

    rf();
    source = 0;
    sink = n + 1;

    for (int i = 1; i <= n; ++ i) {
        if (degout[i] > degin[i]) {
            E.push_back(Edge(i, sink, degout[i] - degin[i], 0, 0));
            g[i].push_back(E.size() - 1);
            E.push_back(Edge(sink, i, 0, 0, 0));
            g[sink].push_back(E.size() - 1);
        } else {
            E.push_back(Edge(source, i, degin[i] - degout[i], 0, 0));
            g[source].push_back(E.size() - 1);
            E.push_back(Edge(i, source, 0, 0, 0));
            g[i].push_back(E.size() - 1);
        }
    }

    for (int i = 1; i <= n; ++ i) {
        for (int j = 1; j <= n; ++ j) {
                if (degin[i] > degout[i] && degout[j] > degin[j]) {
                    E.push_back(Edge(i, j, inf, 0, cost[i][j]));
                    g[i].push_back(E.size() - 1);
                    E.push_back(Edge(j, i, 0, 0, -cost[i][j]));
                    g[j].push_back(E.size() - 1);
                }
        }
    }
    printf("%i\n", ans + maxflow());
    return 0;
}