poj Drainage Ditches

#include<iostream>
using namespace std;
const int inf = 0x7fffffff;
const int MAXN = 210;
const int MAXM = MAXN*MAXN;
int map[MAXN][MAXN];
int dis[MAXN];
int queue[MAXM];
int bef[MAXN];
int num[MAXN];
void set_dis(int end)
{
int top(0),base(0);
memset(dis,-1,sizeof(dis));
memset(num,0,sizeof(num));
queue[top++] = end;
dis[end]=0;num[0] = 1;
while(top!=base)
{
int pre = queue[base++];
for(int i=end-1;i!=0;i--)
{
if(dis[i] != -1 || map[i][pre] == 0)
continue;
dis[i] = dis[pre]+1;
queue[top++] = i;
num[dis[i]]++;
}
}
}
int cmp(int x,int y)
{
if(x<y)
return x;
return y;
}
int remark(int n,int a)
{
int tmp=inf;
for(int i=1;i!=n+1;i++)
if(map[a][i]!=0&&dis[i]>=0)
tmp=cmp(tmp,dis[i]+1);
if(tmp==inf)
tmp=n;
return tmp;
}
int SAP(int n,int s)
{
int j,a = s;int flow(0);
memset(bef,-1,sizeof(bef));
while(dis[s]<n)
{
for(j=1;j!=n+1;j++)
{
if(map[a][j]>0&&dis[a]-1==dis[j])
{
break;
}
}
if(j<=n)
{
bef[j] = a;a = j;
if(a==n)
{
int i = n,max(inf);
while(bef[i]!=-1)
{
max = cmp(max,map[bef[i]][i]);
i = bef[i];
}
i = n;
while(bef[i]!=-1)
{
map[bef[i]][i]-=max;
map[i][bef[i]]+=max;
i = bef[i];
}
flow+=max;a=s;
}
}
else
{
int x = remark(n,a);
num[x]++;num[dis[a]]--;
if(num[dis[a]]==0)
return flow;//间隙优化 gap
dis[a]=x;
if(a!=s)
a=bef[a];
}
}
return flow;
}
int main()
{
int e,n;
//cout<<inf<<endl;
while(cin>>e>>n)
{
memset(map,0,sizeof(map));
while(e--)
{
int a,b,w;
cin>>a>>b>>w;
map[a][b] += w;
}
set_dis(n);
cout<<SAP(n,1)<<endl;
}
return 0;
}