1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
#include <u.h>
#include <libc.h>
#include <bio.h>
#define whsiz (sizeof(wheel)/sizeof(wheel[0]))
double wheel[] =
{
2,10, 2, 4, 2, 4, 6, 2, 6, 4,
2, 4, 6, 6, 2, 6, 4, 2, 6, 4,
6, 8, 4, 2, 4, 2, 4, 8, 6, 4,
6, 2, 4, 6, 2, 6, 6, 4, 2, 4,
6, 2, 6, 4, 2, 4, 2,10,
};
Biobuf bin;
void factor(double);
void
main(int argc, char *argv[])
{
double n;
int i;
char *l;
if(argc > 1) {
for(i=1; i<argc; i++) {
n = atof(argv[i]);
factor(n);
}
exits(0);
}
Binit(&bin, 0, OREAD);
for(;;) {
l = Brdline(&bin, '\n');
if(l == 0)
break;
n = atof(l);
if(n <= 0)
break;
factor(n);
}
exits(0);
}
void
factor(double n)
{
double quot, d, s;
int i;
print("%.0f\n", n);
if(n == 0)
return;
s = sqrt(n) + 1;
while(modf(n/2, ") == 0) {
print(" 2\n");
n = quot;
s = sqrt(n) + 1;
}
while(modf(n/3, ") == 0) {
print(" 3\n");
n = quot;
s = sqrt(n) + 1;
}
while(modf(n/5, ") == 0) {
print(" 5\n");
n = quot;
s = sqrt(n) + 1;
}
while(modf(n/7, ") == 0) {
print(" 7\n");
n = quot;
s = sqrt(n) + 1;
}
d = 1;
for(i=1;;) {
d += wheel[i];
while(modf(n/d, ") == 0) {
print(" %.0f\n", d);
n = quot;
s = sqrt(n) + 1;
}
i++;
if(i >= whsiz) {
i = 0;
if(d > s)
break;
}
}
if(n > 1)
print(" %.0f\n",n);
print("\n");
}
|