poj3013
spfa，说是边的价值=承重*单位价，实际上就是把到达每个结点所需经过的边的单位价之和乘以结点重量之积加起来即可。所以我们就是要让到达每个结点经过的边的单位价格之和最小。这就变成了最短路问题。
这道题用栈超时，用队列能过。所以以后用spfa还是用队列的好。
View Code
#include
<
iostream
>
#include
<
cstdio
>
#include
<
cstdlib
>
#include
<
cstring
>
using
namespace
std;
#define
maxn 150005
struct
Edge
{
int
v, w, next;
} edge[maxn];
int
v, e, ncount;
long
long
weight[maxn];
int
head[maxn];
long
long
stk[maxn], f, r, xtime[maxn];
bool
instk[maxn];
void
input()
{
memset(head,
-
1
,
sizeof
(head));
ncount
=
0
;
scanf(
"
%d%d
"
,
&
v,
&
e);
for
(
int
i
=
0
; i
<
v; i
++
)
scanf(
"
%I64d
"
,
&
weight[i]);
for
(
int
i
=
0
; i
<
e; i
++
)
{
int
a, b, c;
scanf(
"
%d%d%d
"
,
&
a,
&
b,
&
c);
a
--
;
b
--
;
edge[ncount].next
=
head[a];
head[a]
=
ncount;
edge[ncount].v
=
b;
edge[ncount].w
=
c;
ncount
++
;
edge[ncount].next
=
head[b];
head[b]
=
ncount;
edge[ncount].v
=
a;
edge[ncount].w
=
c;
ncount
++
;
}
}
void
spfa()
{
memset(xtime,
-
1
,
sizeof
(xtime));
memset(instk,
0
,
sizeof
(instk));
f
=
0
;
r
=
0
;
stk[r
++
]
=
0
;
instk[
0
]
=
true
;
xtime[
0
]
=
0
;
while
(f
!=
r)
{
int
temp
=
stk[f
++
];
instk[temp]
=
false
;
if
(f
==
maxn)
f
=
0
;
for
(
int
i
=
head[temp]; i
!=
-
1
; i
=
edge[i].next)
{
if
(xtime[edge[i].v]
>
xtime[temp]
+
edge[i].w
||
xtime[edge[i].v]
==
-
1
)
{
xtime[edge[i].v]
=
xtime[temp]
+
edge[i].w;
if
(
!
instk[edge[i].v])
{
stk[r
++
]
=
edge[i].v;
instk[edge[i].v]
=
true
;
if
(r
==
maxn)
r
=
0
;
}
}
}
}
}
void
output()
{
long
long
sum
=
0
;
for
(
int
i
=
0
; i
<
v; i
++
)
{
if
(xtime[i]
==
-
1
)
{
printf(
"
No Answer\n
"
);
return
;
}
sum
+=
weight[i]
*
xtime[i];
}
printf(
"
%I64d\n
"
, sum);
}
int
main()
{
//
freopen("D:\\t.txt", "r", stdin);
int
t;
scanf(
"
%d
"
,
&
t);
while
(t
--
)
{
input();
spfa();
output();
}
return
0
;
}