首先，你在long long和int 的转化上有问题，全改成long long 后82分 @[orekix](/user/917922)
```cpp
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
class Edge {
public:
ll to;
ll weight;
ll next;
Edge(ll to, ll weight, ll next) : to(to), weight(weight), next(next) {}
Edge() {};
};
ll m, n, S, T, cnt = 1;
vector<Edge> graph;
vector<ll> level, head;
void addEdge(ll from, ll to, ll weight) {
graph[++cnt] = Edge(to, weight, head[from]);
head[from] = cnt;
}
bool bfs() {
level = vector<ll>(n, 0);
level[S] = 1;
queue<ll> queue;
queue.emplace(S);
while (!queue.empty()) {
ll u = queue.front();
queue.pop();
for (int i = head[u]; i; i = graph[i].next) {
ll v = graph[i].to;
ll weight = graph[i].weight;
if (!level[v] && weight) {
level[v] = level[u] + 1;
if (v == T) return true;
queue.emplace(v);
}
}
}
return false;
}
long long dfs(ll u, long long inFLow) {
if (u == T) return inFLow;
long long outFlow = 0;
for (ll i = head[u]; i; i = graph[i].next) {
ll v = graph[i].to;
long long weight = graph[i].weight;
if (level[v] == level[u] + 1 && weight) {
long long flow = dfs(v, min(weight, inFLow));
if(!flow) level[v]=0;
graph[i].weight -= flow;
graph[i ^ 1].weight += flow;
inFLow -= flow;
outFlow += flow;
if (!inFLow) break;
}
}
if (outFlow == 0) level[u] = 0;
return outFlow;
}
long long dinic() {
long long maxFlow = 0;
while (bfs()) {
maxFlow += dfs(S, LONG_LONG_MAX);
}
return maxFlow;
}
int main() {
cin >> n >> m >> S >> T;
head = vector<ll>(n + 1, 0);
graph = vector<Edge>(2 * m + 2);
for (int i = 0; i < m; ++i) {
ll from, to; long long weight;
cin >> from >> to >> weight;
addEdge(from, to, weight);
addEdge(to, from, 0);
}
cout << dinic();
}
```
by Code_quantum @ 2023-02-03 18:56:03
剩下的再帮你看一下
by Code_quantum @ 2023-02-03 18:56:40
OK,通过了bfs里面的初始化有一点小问题 @[orekix](/user/917922)
```cpp
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
class Edge {
public:
ll to;
ll weight;
ll next;
Edge(ll to, ll weight, ll next) : to(to), weight(weight), next(next) {}
Edge() {};
};
ll m, n, S, T, cnt = 1;
vector<Edge> graph;
vector<ll> level, head;
void addEdge(ll from, ll to, ll weight) {
graph[++cnt] = Edge(to, weight, head[from]);
head[from] = cnt;
}
bool bfs() {
level = vector<ll>(n+1, 0);
level[S] = 1;
queue<ll> queue;
queue.emplace(S);
while (!queue.empty()) {
ll u = queue.front();
queue.pop();
for (int i = head[u]; i; i = graph[i].next) {
ll v = graph[i].to;
ll weight = graph[i].weight;
if (!level[v] && weight) {
level[v] = level[u] + 1;
if (v == T) return true;
queue.emplace(v);
}
}
}
return false;
}
long long dfs(ll u, long long inFLow) {
if (u == T) return inFLow;
long long outFlow = 0;
for (ll i = head[u]; i; i = graph[i].next) {
ll v = graph[i].to;
long long weight = graph[i].weight;
if (level[v] == level[u] + 1 && weight) {
long long flow = dfs(v, min(weight, inFLow));
if(!flow) level[v]=0;
graph[i].weight -= flow;
graph[i ^ 1].weight += flow;
inFLow -= flow;
outFlow += flow;
if (!inFLow) break;
}
}
if (outFlow == 0) level[u] = 0;
return outFlow;
}
long long dinic() {
long long maxFlow = 0;
while (bfs()) {
maxFlow += dfs(S, LONG_LONG_MAX);
}
return maxFlow;
}
int main() {
cin >> n >> m >> S >> T;
head = vector<ll>(n + 1, 0);
graph = vector<Edge>(2 * m + 2);
for (int i = 0; i < m; ++i) {
ll from, to; long long weight;
cin >> from >> to >> weight;
addEdge(from, to, weight);
addEdge(to, from, 0);
}
cout << dinic();
}
```
by Code_quantum @ 2023-02-03 18:58:19
@[Code_quantum](/user/933880)
谢谢大佬，没注意到是因为level数组初始化大小开始是从0开始的，后来改成从1开始但是忘改数组大小了o(╥﹏╥)o 。
by orekix @ 2023-02-03 19:16:26
@[orekix](/user/917922) 但是这个 Dinic 没有当前弧优化，时间复杂度是假的。
by reveal @ 2023-02-03 19:32:29