LYDSY 1927
题目大意
暂无
题目解法
暂无
RTFC
#include <cstdio>
#include <cstring>
inline int min(int a, int b) { return a < b ? a : b; }
const int inf = 0x3f3f3f3f, maxn = 4010, maxm = 50010;
int head[maxn], next[maxm], to[maxm], cap[maxm], cost[maxm], ecnt;
int que[maxn << 2], dis[maxn], curFlow[maxn], fa[maxn];
bool inq[maxn];
inline void addEdge_impl_(int u, int v, int ca, int co)
{
next[ecnt] = head[u];
head[u] = ecnt;
to[ecnt] = v;
cap[ecnt] = ca;
cost[ecnt] = co;
ecnt++;
}
inline void addEdge(int u, int v, int ca, int co)
{
addEdge_impl_(u, v, ca, co);
addEdge_impl_(v, u, 0, -co);
}
bool MCMF(int S, int T, int &F, int &C)
{
memset(inq, 0, sizeof(inq));
memset(dis, inf, sizeof(dis));
int h = 0, t = 0;
que[t++] = S;
inq[S] = true;
curFlow[S] = inf;
dis[S] = 0;
for (int x; h != t; inq[que[h++]] = false)
for (int i = head[x = que[h]]; ~i; i = next[i])
if (cap[i] > 0 && dis[to[i]] > dis[x] + cost[i])
{
dis[to[i]] = dis[x] + cost[i];
curFlow[to[i]] = min(curFlow[x], cap[i]);
fa[to[i]] = i;
if (!inq[to[i]]) inq[que[t++] = to[i]] = true;
}
if (dis[T] == inf) return false;
F += curFlow[T], C += curFlow[T] * dis[T];
for (int i = T; i != S; i = to[fa[i] ^ 1])
cap[fa[i]] -= curFlow[T], cap[fa[i] ^ 1] += curFlow[T];
return true;
}
int main()
{
memset(head, -1, sizeof(head));
int n, m;
scanf("%d%d", &n, &m);
int S = 0, T = n << 1 | 1;
for (int i = 1, x; i <= n; i++)
{
scanf("%d", &x);
addEdge(S, i, 1, 0);
addEdge(S, n + i, 1, x);
addEdge(n + i, T, 1, 0);
}
for (int i = 1, x, y, z, t; i <= m; i++)
{
scanf("%d%d%d", &x, &y, &z);
if (x > y) t = x, x = y, y = t;
addEdge(x, n + y, 1, z);
}
int C = 0, F = 0;
while (MCMF(S, T, F, C))
;
printf("%d", C);
return 0;
}