ZOJ 1700 Falling Leaves
建立二叉查找树，前序遍历输出
代码
1
#include
<
iostream
>
2
#include
<
stdlib.h
>
3
using
namespace
std;
4
5
struct
node
6
{
7
char
a;
8
node
*
left;
9
node
*
right;
10
};
11
12
void
insert(
char
, node
**
);
13
void
output(node
*
);
14
node
*
modified_search(node
*
,
char
);
15
void
cleartree(node
*
head);
16
17
int
main()
18
{
19
char
hold[
200
][
200
];
20
char
b[
200
];
21
int
i
=
0
;
22
int
count
=
0
;
23
node
*
head
=
NULL;
24
25
//
freopen("test.txt", "r", stdin) ;
26
27
while
(cin
>>
b)
28
{
29
if
(b[
0
]
!=
'
*
'
&&
b[
0
]
!=
'
$
'
)
30
{
31
strcpy(hold[i
++
], b);
32
count
++
;
33
}
34
if
(b[
0
]
==
'
*
'
||
b[
0
]
==
'
$
'
)
35
{
36
for
(
int
i
=
count
-
1
; i
>=
0
; i
--
)
37
{
38
for
(
int
j
=
0
; j
<
strlen(hold[i]); j
++
)
39
{
40
insert(hold[i][j],
&
head);
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}
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}
//
构建二叉树
43
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output(head);
45
cleartree(head);
46
cout
<<
"
\n
"
;
47
if
(b[
0
]
==
'
$
'
)
48
break
;
49
50
count
=
0
;
51
i
=
0
;
52
head
=
NULL;
53
}
54
55
}
56
}
57
//
前序输出
58
void
output(node
*
head)
59
{
60
if
(head
!=
NULL)
61
{
62
cout
<<
head
->
a;
63
output(head
->
left);
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output(head
->
right);
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}
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}
67
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//
释放内存
69
void
cleartree(node
*
head)
70
{
71
if
(head)
72
{
73
if
(head
->
left
==
NULL
&&
head
->
right
==
NULL)
74
{
75
delete head;
76
}
77
else
78
{
79
cleartree(head
->
left);
80
cleartree(head
->
right);
81
delete head;
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}
83
}
84
85
}
86
87
//
建立二叉查找树
88
void
insert(
char
a, node
**
head)
89
{
90
node
*
b;
91
//
查找需要插入的节点
92
node
*
tmp
=
modified_search(
*
head, a);
93
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if
(tmp)
95
{
96
b
=
new
node;
97
if
(b
==
NULL)
98
{
99
//
cout << "FULL";
100
exit(
0
);
101
}
102
b
->
a
=
a;
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b
->
left
=
NULL;
104
b
->
right
=
NULL;
105
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if
(tmp
->
a
<
b
->
a)
107
tmp
->
right
=
b;
108
if
(tmp
->
a
>
b
->
a)
109
tmp
->
left
=
b;
110
111
}
112
else
113
{
114
//
创建头节点
115
if
(
*
head
==
NULL)
116
{
117
*
head
=
new
node;
118
(
*
head)
->
a
=
a;
119
(
*
head)
->
left
=
NULL;
120
(
*
head)
->
right
=
NULL;
121
}
122
}
123
124
125
126
}
127
//
查找需要插入结点的函数
128
//
写得比较复杂
129
node
*
modified_search(node
*
head,
char
a)
130
{
131
132
if
(head
==
NULL
||
head
->
left
==
NULL
&&
head
->
right
==
NULL)
133
{
134
return
head;
135
}
136
else
137
{
138
if
(head
->
a
>
a
&&
head
->
left
==
NULL)
//
已经到底
139
return
head;
140
141
if
(head
->
a
>
a
&&
head
->
left
!=
NULL)
//
还没到底，继续搜索
142
return
modified_search(head
->
left, a);
143
144
if
(head
->
a
<
a
&&
head
->
right
!=
NULL)
//
已经到底
145
return
modified_search(head
->
right, a);
146
147
if
(head
->
a
<
a
&&
head
->
right
==
NULL)
//
还没到底，继续搜索
148
return
head;
149
150
if
(head
->
a
==
a)
//
当发现插入的数重复时，忽略
151
return
NULL;
152
}
153
}