这次没看答案，把去年的代码重新推翻再写了下，确实感觉到很多可以优化的地方，然后这个算法没我想象中的那么难，网络流24题可以安排上了，两个版本

版本1：这个版本是用邻接矩阵，但是后来发现完全可以用前向星

#include <bits/stdc++.h>
using namespace std;
#define limit (1000 + 5)//防止溢出
#define INF 0x3f3f3f3f
#define inf 0x3f3f3f3f3f
#define lowbit(i) i&(-i)//一步两步
#define EPS 1e-6
#define FASTIO  ios::sync_with_stdio(false);cin.tie(0);
#define ff(a) printf("%d\n",a );
#define pi(a,b) pair<a,b>
#define rep(i, a, b) for(ll i = a; i <= b ; ++i)
#define per(i, a, b) for(ll i = b ; i >= a ; --i)
#define MOD 988244353
#define FOPEN freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\data.txt", "rt", stdin)
#define FOUT freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\dabiao.txt", "wt", stdout)
typedef long long ll;
typedef unsigned long long ull;
ll read(){ll sign = 1, x = 0;char s = getchar();while(s > '9' || s < '0' ){if(s == '-')sign = -1;s = getchar();}while(s >= '0' && s <= '9'){x = (x << 3) + (x << 1) + s - '0';s = getchar();}return x * sign;
}//快读
void write(ll x){if(x < 0) putchar('-'),x = -x;if(x / 10) write(x / 10);putchar(x % 10 + '0');
}
int n,m;
int g[limit][limit];
int dist[limit],vis[limit];
int fa[limit];
void init(){memset(dist, INF, sizeof(dist));memset(vis, 0 , sizeof(vis));
}int spfa(){queue<int>q;init();vis[1] = 1;dist[1] = 0;q.push(1);fa[n] = -1;while (q.size()){int u = q.front();q.pop();vis[u] = 0;rep(v ,1,n){if(dist[u] + 1 < dist[v] && g[u][v] > 0){dist[v] = dist[u] + 1;fa[v] = u;if(!vis[v]){vis[v] = 1;q.push(v);}}}}return ~fa[n];
}
int max_flow;
void dinic(){while (spfa()){int min_flow = INF;for(int u = n ; u - 1 ; u = fa[u]){min_flow = min(min_flow, g[fa[u]][u]);}max_flow += min_flow;for(int u = n ; u - 1 ; u = fa[u]){g[fa[u]][u] -= min_flow;g[u][fa[u]] += min_flow;}}
}
int main() {
#ifdef LOCALFOPEN;
#endifwhile (cin>>m>>n) {m = read(), n = read();memset(g, 0 , sizeof(g));rep(i, 1, m) {int x = read(), y = read(), flow = read();g[x][y] += flow;}dinic();write(max_flow),putchar('\n');}return 0;
}

前向星版本：

#include <bits/stdc++.h>
using namespace std;
#define limit (1000000 + 5)//防止溢出
#define INF 0x3f3f3f3f
#define inf 0x3f3f3f3f3f
#define lowbit(i) i&(-i)//一步两步
#define EPS 1e-6
#define FASTIO  ios::sync_with_stdio(false);cin.tie(0);
#define ff(a) printf("%d\n",a );
#define pi(a,b) pair<a,b>
#define rep(i, a, b) for(ll i = a; i <= b ; ++i)
#define per(i, a, b) for(ll i = b ; i >= a ; --i)
#define MOD 988244353
#define FOPEN freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\data.txt", "rt", stdin)
#define FOUT freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\dabiao.txt", "wt", stdout)
typedef long long ll;
typedef unsigned long long ull;
ll read(){ll sign = 1, x = 0;char s = getchar();while(s > '9' || s < '0' ){if(s == '-')sign = -1;s = getchar();}while(s >= '0' && s <= '9'){x = (x << 3) + (x << 1) + s - '0';s = getchar();}return x * sign;
}//快读
void write(ll x){if(x < 0) putchar('-'),x = -x;if(x / 10) write(x / 10);putchar(x % 10 + '0');
}
int n,m,vs,ve;
int head[limit],cnt;
int dist[limit],fa[limit],vis[limit],pre[limit];
struct node{int to, next, flow, w;
}edge[limit<<1];
void add(int u, int v, int flow, int w = 1){edge[cnt].to = v;edge[cnt].flow = flow;edge[cnt].w = w;edge[cnt].next = head[u];head[u] = cnt++;
}
void init(int flag = 0){if(flag){memset(dist, INF, sizeof(dist));memset(vis, 0 , sizeof(vis));}else{memset(head, -1, sizeof(head));cnt = 0;}
}
int spfa(){queue<int>q;init(1);dist[vs] = 0;vis[vs] = 1;q.push(vs);pre[ve] = -1;while (q.size()){int u = q.front();q.pop();vis[u] = 0;for(int i = head[u]; ~i; i = edge[i].next){int v = edge[i].to, w = edge[i].w;int stream = edge[i].flow;if(dist[u] + w < dist[v] && stream > 0){dist[v] = dist[u] + w;pre[v] = i;fa[v] = u;if(!vis[v]){vis[v] = 1;q.push(v);}}}}return ~pre[ve];
}int max_flow,min_cost;
void dinic(){while (spfa()){int min_flow = INF;for(int i = ve; i != vs; i = fa[i]){min_flow = min(min_flow, edge[pre[i]].flow);}max_flow += min_flow;min_cost  += dist[ve] * min_flow;for(int i = ve; i != vs; i = fa[i]){edge[pre[i]].flow -= min_flow;edge[pre[i] ^ 1].flow += min_flow;}}
}
int main() {
#ifdef LOCALFOPEN;
#endifwhile(cin>>n>>m){vs= 1, ve =m;init();rep(i, 1, n){int x= read(),y = read(), floww = read();if(~head[x] || edge[head[x]].flow == 0) {add(x, y, floww);add(y, x, 0);}else{edge[head[x]].flow += floww;}}max_flow = 0;dinic();printf("%d\n", max_flow);}return 0;
}