字典树-trie
描述：将火星文翻译成英文。
反思：好久以前做的，现在又拿来写了个字典树，递归比非递归确实慢，一个小错误导致wa数次。
代码
#include
<
stdio.h
>
#include
<
string
.h
>
#include
<
ctype.h
>
struct
Node {
Node
*
t[
26
];
char
mar[
13
];
Node () {
for
(
int
i
=
0
; i
<
26
; i
++
)
t[i]
=
NULL;
mar[
0
]
=
'
\0
'
;
//
key '\0' 写成了 '/0'
}
};
Node
*
head;
void
build(Node
*
p,
char
*
c1,
char
*
c2) {
if
(
*
c1
==
'
\0
'
) {
strcpy(p
->
mar, c2);
return
;
}
int
k
=
*
c1
-
'
a
'
;
if
(p
->
t[k]
==
NULL) {
p
->
t[k]
=
new
Node;
}
build(p
->
t[k], c1
+
1
, c2);
}
void
find(Node
*
p,
char
*
c1,
char
*
c2) {
if
(
*
c1
==
'
\0
'
) {
if
(p
->
mar[
0
]
!=
'
\0
'
)
strcpy(c2, p
->
mar);
return
;
}
int
k
=
*
c1
-
'
a
'
;
if
(p
->
t[k]
!=
NULL) {
find(p
->
t[k], c1
+
1
, c2);
}
}
int
main()
{
char
c1[
20
], c2[
20
], c[
3010
];
//
freopen("datain", "r", stdin);
//
freopen("dataout", "w", stdout);
while
(scanf(
"
%s
"
, c1)
!=
EOF) {
head
=
new
Node;
while
(scanf(
"
%s
"
, c1)) {
if
(strcmp(c1,
"
END
"
)
==
0
)
break
;
scanf(
"
%s
"
, c2);
build(head, c2, c1);
}
scanf(
"
%s%*c
"
, c1);
while
(gets(c)) {
if
(strcmp(c,
"
END
"
)
==
0
)
break
;
int
len
=
strlen(c);
for
(
int
i
=
0
; i
<
len; ) {
int
j
=
0
;
while
(i
<
len
&&
isalpha(c[i])) {
c1[j
++
]
=
c[i
++
];
}
if
(j
>
0
) {
c1[j]
=
'
\0
'
;
c2[
0
]
=
'
\0
'
;
find(head, c1, c2);
if
(c2[
0
]
!=
'
\0
'
) {
printf(
"
%s
"
, c2);
}
else
{
printf(
"
%s
"
, c1);
}
}
else
{
printf(
"
%c
"
, c[i]);
i
++
;
}
}
printf(
"
\n
"
);
}
}
return
0
;
}
描述：求前缀中包含给定串的单词数。
变形：结点记录的信息是建树时经过该结点的次数。
描述：手机智能拼音输入法[见题]
反思：strcmp()函数搞错，wa数次，查错过错很纠结！
代码
#include
<
stdio.h
>
#include
<
string
.h
>
struct
Node {
Node
*
t[
26
];
int
per;
Node() {
for
(
int
i
=
0
; i
<
26
; i
++
) {
t[i]
=
NULL;
}
per
=
0
;
}
};
char
ans[
110
], cc[
110
];
int
pp;
Node
*
head;
char
dg[
10
][
5
]
=
{
{},
{},
{
3
,
'
a
'
,
'
b
'
,
'
c
'
},
{
3
,
'
d
'
,
'
e
'
,
'
f
'
},
{
3
,
'
g
'
,
'
h
'
,
'
i
'
},
{
3
,
'
j
'
,
'
k
'
,
'
l
'
},
{
3
,
'
m
'
,
'
n
'
,
'
o
'
},
{
4
,
'
p
'
,
'
q
'
,
'
r
'
,
'
s
'
},
{
3
,
'
t
'
,
'
u
'
,
'
v
'
},
{
4
,
'
w
'
,
'
x
'
,
'
y
'
,
'
z
'
}
};
void
build(Node
*
p,
char
*
c,
int
per) {
p
->
per
+=
per;
if
(
*
c
==
'
\0
'
)
return
;
int
k
=
*
c
-
'
a
'
;
if
(p
->
t[k]
==
NULL) {
p
->
t[k]
=
new
Node;
}
build(p
->
t[k], c
+
1
, per);
}
void
find(Node
*
p,
char
*
c,
char
*
c1) {
if
(
*
c
==
'
\0
'
) {
*
c1
=
'
\0
'
;
if
(ans[
0
]
==
'
\0
'
) {
strcpy(ans, cc);
pp
=
p
->
per;
}
else
{
if
(p
->
per
>
pp) {
strcpy(ans, cc);
pp
=
p
->
per;
}
else
if
(p
->
per
==
pp) {
if
(strcmp(ans, cc)
>
0
) {
//
key 写成 ‘<’ 了
strcpy(ans, cc);
}
}
}
return
;
}
int
k
=
*
c
-
'
0
'
;
for
(
int
i
=
1
; i
<=
dg[k][
0
]; i
++
) {
int
j
=
dg[k][i]
-
'
a
'
;
if
(p
->
t[j]
==
NULL)
continue
;
*
c1
=
dg[k][i];
find(p
->
t[j], c
+
1
, c1
+
1
);
}
}
int
main() {
//
freopen("datain", "r", stdin);
//
freopen("dataout", "w", stdout);
int
t, cs
=
1
;
int
w, m, i, j, per;
char
c[
130
], dig[
110
];
scanf(
"
%d
"
,
&
t);
while
(t
--
) {
head
=
new
Node;
scanf(
"
%d
"
,
&
w);
while
(w
--
) {
scanf(
"
%s%d
"
, c,
&
per);
build(head, c, per);
}
printf(
"
Scenario #%d:\n
"
, cs
++
);
scanf(
"
%d
"
,
&
m);
while
(m
--
) {
scanf(
"
%s
"
, dig);
int
len
=
strlen(dig);
for
(i
=
1
; i
<
len; i
++
) {
char
c0[
110
], c1[
110
];
strncpy(c0, dig, i);
c0[i]
=
'
\0
'
;
ans[
0
]
=
'
\0
'
;
pp
=
0
;
//
printf("%s ", c0);
find(head, c0, cc);
//
ans[i] = '\0';
if
(ans[
0
]
==
'
\0
'
) {
printf(
"
MANUALLY\n
"
);
}
else
{
printf(
"
%s\n
"
, ans);
}
}
printf(
"
\n
"
);
}
printf(
"
\n
"
);
}
return
0
;
}
描述：同hdu-1075.
Say_Sth:这次用非递归写的，当然比递归的快点，可以当模板。
字典树模板
#include
<
stdio.h
>
#include
<
string
.h
>
#define
F 26
//
字符集规模
#define
M 13
//
单词最大长度
struct
Node {
Node
*
t[F];
char
word[M];
//
结点保存的信息
Node () {
//
initicalize
for
(
int
i
=
0
; i
<
F; i
++
) {
t[i]
=
NULL;
}
word[
0
]
=
0
;
}
};
Node
*
head;
void
build(Node
*
p,
char
*
c1,
char
*
c2) {
Node
*
p1
=
p;
while
(
*
c1) {
int
k
=
*
c1
-
'
a
'
;
if
(p1
->
t[k]
==
0
) p1
->
t[k]
=
new
Node;
p1
=
p1
->
t[k];
c1
++
;
}
strcpy(p1
->
word, c2);
}
bool
find(Node
*
p,
char
*
c1,
char
*
c2) {
Node
*
p1
=
p;
while
(
*
c1) {
int
k
=
*
c1
-
'
a
'
;
if
(p1
->
t[k]) p1
=
p1
->
t[k];
else
return
false
;
c1
++
;
}
strcpy(c2, p1
->
word);
return
true
;
}
int
main()
{
//
freopen("datain", "r", stdin);
char
c[M
*
3
], c1[M], c2[M];
head
=
new
Node;
while
(gets(c)) {
if
(
!
strcmp(c,
""
))
break
;
sscanf(c,
"
%s%s
"
, c1, c2);
build(head, c2, c1);
}
while
(scanf(
"
%s
"
, c1)
!=
EOF) {
if
(find(head, c1, c2)) {
printf(
"
%s\n
"
, c2);
}
else
{
printf(
"
eh\n
"
);
}
}
return
0
;
}