poj 1637 Sightseeing tour

#include <iostream>
#include <cstdio>
#include <algorithm>
//#include <cstring>
//#include <cmath>
#include <queue>
#include <set>
#define INF 2000000000
#define maxn 210
#define       min(a, b) a < b ?       a : b
using namespace std;

int n, m;
int dis[maxn];
int pre[maxn];
int front[maxn];
int gap[maxn];
int cur[maxn];
int du[maxn];
int index;

struct Edge{
int v;
int w;
int next;
}e[maxn*maxn];

void       init(){

memset( pre, -1, sizeof(pre)       );
memset( du, 0,       sizeof(du)       );
index = 0;
}

void Add( int u, int       v, int w       ){
e[index].v =       v;
e[index].w =       w;
e[index].next =       pre[u];
pre[u] =       index++;

e[index].v       = u;
e[index].w       = 0;
e[index].next = pre[v];
pre[v] = index++;
}

int maxflow_sap( int s, int t       ){
memset( dis, 0,       sizeof(dis)       );
memset( gap, 0,       sizeof(gap)       );
memset( front, -1, sizeof(front)       );
int       i;
for ( i       = 0; i <= t; i++       ){
cur[i] =       pre[i];
}
int flow = INF, u       = s, maxflow = 0;
gap[s] = t + 1;

while ( dis[s] <       t+1       ){
for ( i = cur[u]; i       != -1; i = e[i].next       ){
if ( dis[u] ==       dis[e[i].v] + 1       && e[i].w > 0       ){
break;
}
}
cur[u]       =       i;

if ( cur[u] !=       -1       ){
flow       = min( flow, e[i].w       );
front[e[i].v]       =       u;
u       =       e[i].v;
if ( u == t       ){
maxflow       +=       flow;
for ( i = front[t];       i != -1; i = front[i]       ){
e[cur[i]].w       -=       flow;
e[cur[i]^1].w +=       flow;
}
flow       =       INF;
u       =       s;
}
}
else{
int mindis = t+2;
for ( i = pre[u]; i       != -1; i = e[i].next       ){
if ( mindis >       dis[e[i].v] + 1       && e[i].w > 0       ){
mindis       = dis[e[i].v] +       1;
cur[u]       =       i;
}
}
gap[dis[u]]--;
if ( !gap[dis[u]]       ){
break;
}
dis[u]       =       mindis;
gap[mindis]++;
if ( u != s       ){
u       =       front[u];
}
}
}
return       maxflow;
}

int       main(){
int       T, i;
scanf("%d",       &T);
while ( T--       ){
init();
scanf("%d%d", &n, &m);
for ( i = 0; i < m; i++       ){
int a, b,       c;
scanf("%d%d%d", &a, &b, &c);
du[a]++;
du--;
[b]if ( !c && a != b       ){
Add(       a, b, 1       );
}
}
int flag = 0, x = 0;;
for ( i = 1; i <= n; i++       ){
if ( du[i] %2       ){
flag       = 1;
break;
}

if ( du[i] >       0       ){
Add(       0, i, du[i]/2       );
x       += du[i]/2;
}
else if (       du[i] < 0       ){
Add(       i, n+1, -du[i]/2       );
//x +=       -du[i]/2;
}
}
if ( !flag && x ==       maxflow_sap( 0, n+1 )       ){
printf("possible\n");
}
else{
printf("impossible\n");
}
}
return 0;
}