poj2112
二分加网络流，开始虽然写了floyd，但是没有调用，导致错了许多次。
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#include
<
iostream
>
#include
<
cstdio
>
#include
<
cstdlib
>
#include
<
cstring
>
using
namespace
std;
#define
N 300
#define
inf 10000000
struct
Edge
{
int
x, y, nxt;
int
c;
} bf[N
*
N];
int
k, c, m, n, s, t;
int
map[N][N];
int
ne, head[N], cur[N], ps[N
*
N], dep[N];
void
floyed()
{
for
(
int
i
=
1
; i
<=
n; i
++
)
for
(
int
j
=
1
; j
<=
n; j
++
)
for
(
int
k
=
1
; k
<=
n; k
++
)
if
(map[j][i]
!=
inf
&&
map[i][k]
!=
inf)
if
(map[j][i]
+
map[i][k]
<
map[j][k])
map[j][k]
=
map[j][i]
+
map[i][k];
}
void
addedge(
int
x,
int
y,
int
c)
{
bf[ne].x
=
x;
bf[ne].y
=
y;
bf[ne].c
=
c;
bf[ne].nxt
=
head[x];
head[x]
=
ne
++
;
bf[ne].x
=
y;
bf[ne].y
=
x;
bf[ne].c
=
0
;
bf[ne].nxt
=
head[y];
head[y]
=
ne
++
;
}
int
flow(
int
n,
int
s,
int
t)
{
int
tr, res
=
0
;
int
i, j, k, f, r, top;
while
(
1
)
{
memset(dep,
-
1
, n
*
sizeof
(
int
));
for
(f
=
dep[ps[
0
]
=
s]
=
0
, r
=
1
; f
!=
r;)
for
(i
=
ps[f
++
], j
=
head[i]; j; j
=
bf[j].nxt)
{
if
(bf[j].c
&&
-
1
==
dep[k
=
bf[j].y])
{
dep[k]
=
dep[i]
+
1
;
ps[r
++
]
=
k;
if
(k
==
t)
{
f
=
r;
break
;
}
}
}
if
(
-
1
==
dep[t])
break
;
memcpy(cur, head, n
*
sizeof
(
int
));
for
(i
=
s, top
=
0
;;)
{
if
((i
==
t))
{
for
(k
=
0
, tr
=
inf; k
<
top;
++
k)
if
(bf[ps[k]].c
<
tr)
tr
=
bf[ps[f
=
k]].c;
for
(k
=
0
; k
<
top;
++
k)
bf[ps[k]].c
-=
tr, bf[ps[k]
^
1
].c
+=
tr;
res
+=
tr;
i
=
bf[ps[top
=
f]].x;
}
for
(j
=
cur[i]; cur[i]; j
=
cur[i]
=
bf[cur[i]].nxt)
if
(bf[j].c
&&
dep[i]
+
1
==
dep[bf[j].y])
break
;
if
(cur[i])
{
ps[top
++
]
=
cur[i];
i
=
bf[cur[i]].y;
}
else
{
if
(
0
==
top)
break
;
dep[i]
=
-
1
;
i
=
bf[ps[
--
top]].x;
}
}
}
return
res;
}
bool
ok(
int
d)
{
ne
=
2
;
memset(head,
0
,
sizeof
(head));
s
=
0
;
t
=
n
+
1
;
for
(
int
i
=
1
; i
<=
k; i
++
)
addedge(i, t, m);
for
(
int
i
=
k
+
1
; i
<=
n; i
++
)
addedge(s, i,
1
);
for
(
int
i
=
k
+
1
; i
<=
n; i
++
)
for
(
int
j
=
1
; j
<=
k; j
++
)
if
(map[i][j]
<=
d)
addedge(i, j,
1
);
int
ret
=
flow(n
+
2
, s, t);
return
(ret
==
c);
}
int
binarysearch()
{
int
l
=
0
;
int
r
=
20000
;
int
mid;
while
(l
<
r)
{
mid
=
(l
+
r)
/
2
;
if
(ok(mid))
r
=
mid;
else
l
=
mid
+
1
;
}
return
l;
}
int
main()
{
//
freopen("t.txt", "r", stdin);
scanf(
"
%d%d%d
"
,
&
k,
&
c,
&
m);
n
=
c
+
k;
for
(
int
i
=
1
; i
<=
n; i
++
)
for
(
int
j
=
1
; j
<=
n; j
++
)
{
scanf(
"
%d
"
,
&
map[i][j]);
if
(map[i][j]
==
0
&&
(i
!=
j))
map[i][j]
=
inf;
}
floyed();
int
ans
=
binarysearch();
printf(
"
%d\n
"
, ans);
return
0
;
}