Poj 3114 countries in war

 

 

Water...

Code:

 

# Include <iostream>
# Include <cstdlib>
# Include <cstring>
# Include <cstdio>
# Include <queue>
Using namespace STD;

Const int maxn = 510;
Const int maxm = 510*510;
Const int INF = 0x3f3f3f;

Struct edge
{
Int V, W;
Int next;
} Edge [maxm], edge2 [maxm];

Int n, m;
Int CNT, cnt2;
Int SCNT, top, TOT;

Int first [maxn], low [maxn], dfn [maxn], stack [maxn], INS [maxn];
Int d [maxn];
Int first2 [maxn];
Int belong [maxm];

Char STR [51] = "Nao e possivel entregar a Carta ";

Void Init ()
{
CNT = cnt2 = 0;
SCNT = Top = tot = 0;
Memset (first,-1, sizeof (first ));
Memset (first2,-1, sizeof (first2 ));
Memset (dfn, 0, sizeof (dfn ));
Memset (INS, 0, sizeof (INS ));
}

Void read_graph (int u, int V, int W)
{
Edge [CNT]. V = V, edge [CNT]. W = W;
Edge [CNT]. Next = first [u], first [u] = CNT ++;
}

Void read_graph2 (int u, int V, int W)
{
Edge2 [cnt2]. V = V, edge2 [cnt2]. W = W;
Edge2 [cnt2]. Next = first2 [u], first2 [u] = cnt2 ++;
}

Void DFS (int u)
{
Int V;
Dfn [u] = low [u] = ++ tot;
Stack [top ++] = u;
INS [u] = 1;
For (int e = first [u]; e! =-1; E = edge [e]. Next)
{
V = edge [e]. V;
If (! Dfn [v])
{
DFS (v );
Low [u] = min (low [u], low [v]);
}
Else if (INS [v])
{
Low [u] = min (low [u], dfn [v]);
}
}
If (dfn [u] = low [u])
{
SCNT ++;
Do
{
V = stack [-- top];
Belong [v] = SCNT;
INS [v] = 0;
} While (u! = V );
}
}

Void Tarjan ()
{
For (INT v = 1; v <= N; V ++) if (! Dfn [v])
DFS (v );
}

Void spfa (int src)
{
Queue <int> q;
Bool INQ [maxn] = {0 };
For (INT I = 1; I <= N; I ++) d [I] = (I = SRC )? 0: INF;
Q. Push (SRC );
While (! Q. Empty ())
{
Int x = Q. Front (); q. Pop ();
INQ [x] = 0;
For (int e = first2 [X]; e! =-1; E = edge2 [e]. Next)
{
Int v = edge2 [e]. V, W = edge2 [e]. W;
If (d [v]> d [x] + W)
{
D [v] = d [x] + W;
If (! INQ [v])
{
INQ [v] = 1;
Q. Push (v );
}
}
}
}
}

Int read_case ()
{
Init ();
Scanf ("% d", & N );
If (! N) return 0;
Scanf ("% d", & M );
While (M --)
{
Int U, V, W;
Scanf ("% d", & U, & V, & W );
Read_graph (U, V, W );
}
Return 1;
}

Void build ()
{
Tarjan ();
For (INT u = 1; U <= N; U ++)
{
For (int e = first [u]; e! =-1; E = edge [e]. Next)
{
Int v = edge [e]. V, W = edge [e]. W;
If (belong [u]! = Belong [v])
{
Read_graph2 (U, V, W );
}
Else read_graph2 (u, v, 0 );
}
}
}

Void solve ()
{
Int Q;
Build ();
Scanf ("% d", & Q );
While (Q --)
{
Int S, E;
Scanf ("% d", & S, & E );
Spfa (s );
If (d [e]! = Inf) printf ("% d \ n", d [e]);
Else printf ("% s \ n", STR );
}
Printf ("\ n ");
}

Int main ()
{
While (read_case ())
{
Solve ();
}
Return 0;
}