不懂就问，卡常后的Dinic比没有卡常的还慢

卡常：

#include<stdio.h>
#define N 209
#define M 5009

struct node
{
    int v, w, nxt;
}e[M << 1];

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;
}

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;
}

int s, t;

int dis[N], now[N];

#include<cstring>

using std::memset;

#include<queue>

using std::queue;

inline bool bfs()
{
    memset(dis, -1, sizeof dis);
    register int u, v, w, i;
    queue < int > q;
    q.push(s);
    dis[s] = 0;
    now[s] = head[s];
    while (!q.empty())
    {
        u = q.front();
        q.pop();
        for (i = head[u];i;i = e[i].nxt)
        {
            v = e[i].v, w = e[i].w;
            if (w > 0 && dis[v] == -1)
            {       
                dis[v] = dis[u] + 1;
                now[v] = head[v];
                if (v == t)
                    return 1;
                q.push(v);
            }
        }
    }
    return 0;
}

inline int min(int a, int b)
{
    return a < b ? a : b;
}

#define ll long long

int dfs(register int u, register int flow = 1e9)
{
    if (u == t)
        return flow;
    register int lost = flow, v, w, k;
    for (register int i = now[u];i && lost;i = e[i].nxt, now[u] = i)
    {
        v = e[i].v, w = e[i].w;
        if (dis[v] == dis[u] + 1 && w > 0)
        {
            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(), u, v, w;
    register ll ans = 0;
    s = read(), t = read();
    while (m --)
        u = read(), v = read(), w = read(), add(u, v, w), add(v, u, 0);
    while (bfs())
        ans += dfs(s);
    printf("%lld", ans);

    return 0;
}

未卡常：

#include<stdio.h>
#define N 409
#include<queue>
using namespace std;
#define M 10009

int dis[N];

struct node
{
    int v, w, nxt;
}e[M << 1];

int head[N], cnt = 1, now[N];

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;
}

inline int read()
{
    register int ret = 0, f = 1;
    register char ch = getchar();
    while (ch < '0' || ch > '9')
        (ch == '-') ? f = -1 : 0, ch = getchar();
    while (ch >= '0' && ch <= '9')
        ret = (ret << 1) + (ret << 3) + (ch ^ 48), ch = getchar();
    return ret * f;
}

int n, s, t;

inline bool bfs()
{
    for (register int i = 1;i <= n;++ i)
        dis[i] = -1;
    queue < int > q;
    dis[s] = 0;
    q.push(s);
    now[s] = head[s];
    while (!q.empty())
    {
        register int u = q.front();
        q.pop();
        for (register int i = head[u];i;i = e[i].nxt)
            if (e[i].w > 0 && dis[e[i].v] == -1)//构建分层图
            {
                int v = e[i].v;
                now[v] = head[v];
                dis[v] = dis[u] + 1;
                if (v == t)
                    return 1;//找到有路径
                q.push(v);
            }
    }
    return 0;//没找到
}

inline long long min(long long a, long long b) {return a < b ? a : b;}

long long dfs(register int u, register long long sum = 1e9)
{
    if (u == t)
        return sum;
    register long long lost = sum;
    for (register int i = now[u];i && lost;i = e[i].nxt)
    {
        now[u] = i;
        int v = e[i].v, w = e[i].w;
        if (dis[v] == dis[u] + 1 && w > 0)//保证不是同一个层并且可以流动
        {
            int k = dfs(v, min(w, lost));//尽量让少的去流，也就是 EK 的想法
            if (!k)//没有，那就真没有
            {
                dis[e[i].v] = -1;
                continue;
            }
            lost -= k;
            e[i].w -= k;
            e[i ^ 1].w += k;
        }
    }
    return sum - lost;
}

inline long long Dinic()
{
    register long long ret = 0;
    while (bfs())
        ret += dfs(s);
    return ret;
}

int main()
{
    n = read();
    register int m = read();
    s = read(), t = read();
    register int u, v, w;
    while (m --)
        u = read(), v = read(), w = read(), add(u, v, w), add(v, u, 0);
    printf("%lld", Dinic());

    return 0;
}