@[GTAISHAN](/user/502247) bfs最后没返回值，不用判重，
by char_cha_ch @ 2022-12-12 15:31:36
@[kirihara233](/user/701221) %%%您能在讲清楚点么，今天刚学没太明白
by GTAISHAN @ 2022-12-12 15:39:12
@[GTAISHAN](/user/502247) 感觉细节问题可能有点多。通常跑网络流都不用判重的，不为什么。你想，重边，依然还是可以流过去的对吧？除了这个知识点的问题可能没多少了。主要是注意一般 `dis` 数组初始值为 `0` ，搞 `inf` 的话害怕值对不上。而且 `next` 里面 `STL` 有，一般都用 `nxt`。贴一份我的（话说你 `Dinic` 跑的比 `EK` 还慢耶
```cpp
#include<cstdio>
#define N 209
#define M 10009
inline int read()
{
register int ret = 0;
register bool f = 1;
register char ch = getchar();
while (ch < '0' || ch > '9')
(ch == '-') ? f = 0 : 0, ch = getchar();
while (ch >= '0' && ch <= '9')
ret = (ret << 1) + (ret << 3) + (ch ^ 48), ch = getchar();
return f ? ret : -ret;
}
struct node
{
int v, w, nxt;
}e[M];
int head[N], cnt = 1;
inline void add(int u, int v, int w)
{
e[++ cnt].v = v, e[cnt].w = w, e[cnt].nxt = head[u], head[u] = cnt;
}
int dis[N], now[N];
#include<queue>
using std::queue;
#include<cstring>
using std::memset;
int s, t;
inline bool bfs()
{
memset(dis, -1, sizeof dis);
queue < int > q;
q.push(s);
dis[s] = 0;
now[s] = head[s];
register int u, v, i;
while (!q.empty())
{
u = q.front();
q.pop();
for (i = head[u];i;i = e[i].nxt)
{
v = e[i].v;
if (e[i].w > 0 && dis[v] == -1)
{
dis[v] = dis[u] + 1;
now[v] = head[v];
if (v == t)
return 1;
q.push(v);
}
}
}
return 0;
}
#define min(a, b) (a < b ? a : b)
int dfs(register int u, register int flow = 1e9)
{
if (u == t)
return flow;
register int lost = flow, i, v, w, k;
for (i = now[u];i && lost;i = e[i].nxt)
{
v = e[i].v, w = e[i].w;
if (w > 0 && dis[v] == dis[u] + 1)
{
k = dfs(v, min(lost, w));
if (!k)
{
dis[v] = -1;
continue;
}
lost -= k;
e[i].w -= k;
e[i & 1].w += k;
}
}
return flow - lost;
}
int main()
{
register int n = read(), m = read();
s = read(), t = read();
register int u, v, i;
register long long ans = 0;
for (i = 1;i <= m;++ i)
u = read(), v = read(), add(u, v, read()), add(v, u, 0);
while (bfs())
ans += dfs(s);
printf("%lld", ans);
return 0;
}
```
~~每日信息学默写内容~~
by char_cha_ch @ 2022-12-12 15:48:40
@[kirihara233](/user/701221) thx
by GTAISHAN @ 2022-12-12 15:51:42