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| #include <bits/stdc++.h>
#pragma optimization_level 3
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
#define MAX_N 2222
#define ll long long
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vall3 vector<array<ll,3>>
#define vll vector<ll>
#define vs vector<string>
#define usll unordered_set<ll>
#define vvs vector<vs>
#define vvll vector<vll>
#define all(a) begin(a), end(a)
using namespace std;
ll V, E, source = 2018, sink = 2019;
ll path[MAX_N], cost[MAX_N][MAX_N], flo[MAX_N][MAX_N], cap[MAX_N][MAX_N];
bool bfs(ll u, ll v, vvll& adj) {
bool inc[MAX_N];
vll w(MAX_N, 987654321);
memset(path, 0, sizeof path);
memset(inc, 0, sizeof inc);
queue<ll> q;
q.push(u);
w[u] = 0;
inc[u] = true;
while(!q.empty()) {
auto n = q.front(); q.pop();
inc[n] = false;
for(auto& m : adj[n]) {
if(cap[n][m] - flo[n][m] > 0 and cost[n][m] + w[n] < w[m]) {
w[m] = w[n] + cost[n][m];
path[m] = n;
if(!inc[m]) {
inc[m] = true;
q.push(m);
}
}
}
}
return path[v] != 0;
}
ll solve(vvll& adj) {
ll res = 0;
while(bfs(source, sink, adj)) {
ll vv = sink, mi = INT_MAX;
while(source != vv) {
ll uu = path[vv];
mi = min(mi, cap[uu][vv] - flo[uu][vv]);
vv = uu;
}
vv = sink;
while(source != vv) {
ll uu = path[vv];
res += mi * cost[uu][vv];
flo[uu][vv] += mi;
flo[vv][uu] -= mi;
vv = uu;
}
}
return res;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.setf(ios::fixed);
cout.precision(6);
while (true) {
cin>>V>>E;
if(cin.eof()) exit(0);
memset(flo, 0, sizeof(flo));
memset(cost, 0, sizeof(cost));
memset(cap, 0, sizeof(cap));
ll u, v, w;
vvll adj(MAX_N);
adj[source].push_back(1 * 2); adj[1 * 2].push_back(source); cap[source][1 * 2] = 2;
adj[sink].push_back(V * 2 + 1); adj[V * 2 + 1].push_back(sink); cap[V * 2 + 1][sink] = 2;
adj[1 * 2].push_back(1 * 2 + 1); adj[1 * 2 + 1].push_back(1 * 2); cap[1 * 2][1 * 2 + 1] = 2;
adj[V * 2].push_back(V * 2 + 1); adj[V * 2 + 1].push_back(V * 2); cap[V * 2][V * 2 + 1] = 2;
for(ll i = 2; i < V; i++) {
adj[i * 2].push_back(i * 2 + 1);
adj[i * 2 + 1].push_back(i * 2);
cap[i * 2][i * 2 + 1] = 1;
}
while(E--) {
cin>>u>>v>>w;
u = u * 2 + 1;
v = v * 2;
adj[u].push_back(v);
adj[v].push_back(u);
cap[u][v] = 1;
cost[u][v] += w;
cost[v][u] += -w;
}
cout<<solve(adj)<<'\n';
}
return 0;
}
|
