hdu1532 Drainage Ditches (Dinic)

#include <stdio.h>
#include <string.h>
#define INF 0x7fffffff
#define MAXN 202

struct node
{
int to,cap,next;
}edge[MAXN<<1];

int head[MAXN],level[MAXN],queue[MAXN];
int tot,src,dest;

int Scan()
{
char ch;
int ret=0;
while((ch=getchar())<'0'||ch>'9');
while(ch>='0'&&ch<='9')
{
ret=ret*10+(ch-'0');
ch=getchar();
}
return ret;
}

int getMin(int x,int y)
{
return x<y?x:y;
}

void addEdge(int m)
{
int u,v,val;
tot=0;
memset(head,-1,sizeof(head));
while(m--)
{
u=Scan();
v=Scan();
val=Scan();
edge[tot].to=v;
edge[tot].cap=val;
edge[tot].next=head[u];
head[u]=tot++;

edge[tot].to=u;
edge[tot].cap=0;
edge[tot].next=head[v];
head[v]=tot++;
}
}

int BFS()
{
int front=0,rear=1,v,i;
memset(level,0,sizeof(level));
queue[0]=src;
level[src]=1;
while(front<rear)
{
v=queue[front++];
if(v==dest)
return 1;
for(i=head[v];i!=-1;i=edge[i].next)
{
if(!level[edge[i].to]&&edge[i].cap>0)
{
level[edge[i].to]=level[v]+1;
queue[rear++]=edge[i].to;
}
}
}
return 0;
}

int DFS(int cur,int maxf)
{
int ret=0,i,temp,v;
if(cur==dest)
return maxf;
for(i=head[cur];i!=-1;i=edge[i].next)
{
v=edge[i].to;
if(edge[i].cap>0&&level[v]==level[cur]+1)
{
temp=DFS(v,getMin(maxf-ret,edge[i].cap));
edge[i].cap-=temp;
edge[i^1].cap+=temp;
ret+=temp;
if(maxf==ret)
return ret;
}
}
return ret;
}

int main()
{
int n,m,maxflow,temp;
while(scanf("%d %d",&m,&n)!=EOF)
{
addEdge(m);
src=1,dest=n;
maxflow=0;
while(BFS())
{
maxflow+=DFS(src,INF);
}
printf("%d\n",maxflow);
}
return 0;
}