学长的代码
#include<stdio.h>
#include<string.h>
#include<queue>
#include<algorithm>
using namespace std;
const int MAXN = 1005;
const int oo = 1e9+7;
struct Edge
{
int v, flow, next;
}edge[MAXN];
int Head[MAXN], cnt;
int Layer[MAXN];
void InIt()
{
cnt = 0;
memset(Head, -1, sizeof(Head));
}
void AddEdge(int u, int v, int flow)
{
edge[cnt].v = v;
edge[cnt].flow = flow;
edge[cnt].next = Head[u];
Head[u] = cnt++;
swap(u, v);
edge[cnt].v = v;
edge[cnt].flow = 0;
edge[cnt].next = Head[u];
Head[u] = cnt++;
}
bool BFS(int start, int End)
{
memset(Layer, 0, sizeof(Layer));
queue<int> Q;
Q.push(start);
Layer[start] = 1;
while(Q.size())
{
int u = Q.front();Q.pop();
if(u == End)return true;
for(int j=Head[u]; j!=-1; j=edge[j].next)
{
int v = edge[j].v;
if(Layer[v] == 0 && edge[j].flow)
{
Layer[v] = Layer[u] + 1;
Q.push(v);
}
}
}
return false;
}
int DFS(int u, int MaxFlow, int End)
{
if(u == End)return MaxFlow;
int uflow = 0;
for(int j=Head[u]; j!=-1; j=edge[j].next)
{
int v = edge[j].v;
if(Layer[v]==Layer[u]+1 && edge[j].flow)
{
int flow = min(edge[j].flow, MaxFlow-uflow);
flow = DFS(v, flow, End);
edge[j].flow -= flow;
edge[j^1].flow += flow;
uflow += flow;
if(uflow == MaxFlow)
break;
}
}
if(uflow == 0)
Layer[u] = 0;
return uflow;
}
int Dinic(int start, int End)
{
int MaxFlow = 0;
while(BFS(start, End) == true)
MaxFlow += DFS(start, oo, End);
return MaxFlow;
}
int main()
{
int N, M;
while(scanf("%d%d", &M, &N) != EOF)
{
int u, v, flow;
InIt();
while(M--)
{
scanf("%d%d%d", &u, &v, &flow);
AddEdge(u, v, flow);
}
printf("%d
", Dinic(1, N));
}
return 0;
}