组合算法（从几个数字中选几个然后组合）
组合算法，很不错，可以拿来选福彩双色球33选6，哈哈！
代码
private
void
button1_Click(
object
sender, EventArgs e)
{
int
n
=
33
;
int
m
=
6
;
string
[]
set
=
new
string
[n];
for
(
int
i
=
0
; i
<
n; i
++
)
{
set
[i]
=
(i).ToString().PadLeft(
2
,
'
0
'
);
}
List
<
string
>
result;
GC.Collect();
result
=
GetCombinationF2(
set
, m);
//
n=20 about 44ms, n=40 about 6s
//
result = GetCombinationF3(set, m);
//
n=20 about 16ms n=40 about 2.5s
//
result = GetCombinationF4(set, m);
//
n=20 about 95ms n=40 about 13s
for
(
int
i
=
0
; i
<
10
; i
++
)
{
this
.txtResult.Text
+=
result[i]
+
"
\r\n
"
;
}
}
#region
组合算法
#region
组合算法2(非递归方法)
static
List
<
string
>
GetCombinationF2(
string
[] strArray,
int
selectCount)
{
int
totalCount
=
strArray.Length;
int
[] currentSelect
=
new
int
[selectCount];
int
last
=
selectCount
-
1
;
List
<
string
>
output
=
new
List
<
string
>
();
string
s;
//
付初始值
for
(
int
i
=
0
; i
<
selectCount; i
++
)
currentSelect[i]
=
i;
while
(
true
)
{
s
=
""
;
//
输出部分,生成的时候从0计数,所以输出的时候+1
for
(
int
i
=
0
; i
<
selectCount; i
++
)
{
s
+=
strArray[currentSelect[i]]
+
"
\t
"
;
}
output.Add(s);
//
如果不进位
if
(currentSelect[last]
<
totalCount
-
1
)
currentSelect[last]
++
;
else
{
//
进位部分
int
position
=
last;
while
(position
>
0
&&
currentSelect[position
-
1
]
==
currentSelect[position]
-
1
)
position
--
;
if
(position
==
0
)
break
;
currentSelect[position
-
1
]
++
;
for
(
int
i
=
position; i
<
selectCount; i
++
)
currentSelect[i]
=
currentSelect[i
-
1
]
+
1
;
}
}
return
output;
}
#endregion
#region
组合算法3
static
List
<
string
>
GetCombinationF3(
string
[] data,
int
count)
{
Dictionary
<
string
,
int
>
dic
=
new
Dictionary
<
string
,
int
>
();
List
<
string
>
output
=
new
List
<
string
>
();
for
(
int
i
=
0
; i
<
data.Length; i
++
)
{
dic.Add(data[i], i);
}
SelectN(dic, data, count,
1
,
ref
output);
return
output;
}
static
void
SelectN(Dictionary
<
string
,
int
>
dd,
string
[] data,
int
count,
int
times,
ref
List
<
string
>
output)
{
//
当前字典中的key与原始数据中值大于自身的每个key组合，比如第一轮递归中，01与02-33这些数组合，02与03-33这些数组合。递归五次，即可从33个数中选出6个。
Dictionary
<
string
,
int
>
dic
=
new
Dictionary
<
string
,
int
>
();
foreach
(KeyValuePair
<
string
,
int
>
kv
in
dd)
{
for
(
int
i
=
kv.Value
+
1
; i
<
data.Length; i
++
)
{
if
(times
<
count
-
1
)
{
dic.Add(kv.Key
+
"
\t
"
+
data[i], i);
}
else
{
output.Add(kv.Key
+
"
\t
"
+
data[i]);
//
不考虑输出，将此句注释掉
}
}
}
times
++
;
if
(dic.Count
>
0
) SelectN(dic, data, count, times,
ref
output);
}
#endregion
#region
组合算法4
static
List
<
string
>
GetCombinationF4(
string
[] data,
int
count)
{
List
<
string
>
output
=
new
List
<
string
>
();
int
len
=
data.Length;
string
start
=
"
1
"
.PadRight(count,
'
1
'
).PadRight(len,
'
0
'
);
string
s;
while
(start
!=
string
.Empty)
{
s
=
""
;
for
(
int
i
=
0
; i
<
len; i
++
)
if
(start[i]
==
'
1
'
) s
+=
data[i]
+
"
\t
"
;
output.Add(s);
start
=
GetNext(start);
}
return
output;
}
static
string
GetNext(
string
str)
{
string
next
=
string
.Empty;
int
pos
=
str.IndexOf(
"
10
"
);
if
(pos
<
0
)
return
next;
else
if
(pos
==
0
)
return
"
01
"
+
str.Substring(
2
);
else
{
int
len
=
str.Length;
next
=
str.Substring(
0
, pos).Replace(
"
0
"
,
""
).PadRight(pos,
'
0
'
)
+
"
01
"
;
if
(pos
<
len
-
2
) next
+=
str.Substring(pos
+
2
);
}
return
next;
}
#endregion
#endregion