dfs ZOJ 1711 Sum It Up
这几天学，BFS和DFS算法，参照网上找的程序，对照着写的。
所有的排列组合问题，基本是基于DFS算法的思路而来的
Sum It Up
1
#include
<
iostream
>
2
using
namespace
std;
3
4
5
int
t;
6
int
n;
7
int
num[
12
];
8
int
rcd[
12
];
9
int
usedtimes[
12
];
10
int
differentnums;
11
bool
isfind
=
false
;
12
void
norepeat_combination(
int
,
int
);
13
void
print(
int
);
14
int
main()
15
{
16
int
count
=
0
;
17
int
a;
18
bool
flag;
19
//
freopen("test.txt","r",stdin);
20
while
(cin
>>
t
>>
n
&&
!
(t
==
0
&&
n
==
0
) )
21
{
22
for
(
int
i
=
0
; i
<
n; i
++
)
23
{
24
usedtimes[i]
=
1
;
25
}
26
flag
=
true
;
27
for
(
int
i
=
0
; i
<
n; i
++
)
28
{
29
cin
>>
a;
30
for
(
int
j
=
0
; j
<
count; j
++
)
31
{
32
if
(a
==
num[j])
33
{
34
flag
=
false
;
35
usedtimes[j]
++
;
36
}
37
}
38
if
(flag)
39
{
40
num[count]
=
a;
41
count
++
;
42
43
}
44
flag
=
true
;
45
}
46
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n
=
count;
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cout
<<
"
Sums of
"
<<
t
<<
"
:
"
<<
endl;
49
norepeat_combination(
0
,
0
);
50
if
(
!
isfind)
51
{
52
cout
<<
"
NONE
"
<<
endl;
53
}
54
isfind
=
false
;
55
count
=
0
;
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}
57
return
0
;
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}
59
int
sum;
60
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//
生成不重复组合，类似DFS过程
62
void
norepeat_combination(
int
len,
int
current)
63
{
64
sum
=
0
;
65
for
(
int
i
=
0
; i
<
len; i
++
)
66
{
67
sum
+=
rcd[i];
68
}
69
if
(sum
==
t)
70
{
71
isfind
=
true
;
72
print(len);
73
}
74
else
75
{
76
for
(
int
i
=
current; i
<
n; i
++
)
77
{
78
if
(usedtimes[i])
79
{
80
usedtimes[i]
--
;
81
rcd[len]
=
num[i];
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norepeat_combination(len
+
1
, i);
//
这里不是i+1，要把所有重复的都用完，才填入下一个不同的数字
83
usedtimes[i]
++
;
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}
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}
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}
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88
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}
90
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void
print(
int
len)
92
{
93
for
(
int
i
=
0
; i
<
len; i
++
)
94
{
95
cout
<<
rcd[i];
96
if
(i
!=
len
-
1
)
97
{
98
cout
<<
"
+
"
;
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}
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}
101
cout
<<
endl;
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}
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