forked from alxsoares/topcoder-6
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathEigenVector.java
More file actions
86 lines (62 loc) · 1.39 KB
/
Copy pathEigenVector.java
File metadata and controls
86 lines (62 loc) · 1.39 KB
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
/*
* SRM192-D2-1000
* SOLVED
*/
import static java.lang.Math.*;
public class EigenVector {
static int MN = 9;
public int[] findEigenVector(String[] A) {
int[][] m = new int[A.length][A.length];
for (int i = 0; i < m.length; i++) {
String[] parts = A[i].split(" ");
for (int j = 0; j < m[i].length; j++)
m[i][j] = Integer.valueOf(parts[j]);
}
int[] v = new int[A.length];
findVector(v, m, 0, MN);
return v;
}
private boolean findVector(int[] v, int[][] m, int i, int n) {
if (i == v.length)
return n < MN && isEigen(v, m);
if (n == MN) {
for (int k = 0; k <= n; ++k) {
v[i] = k;
if (findVector(v, m, i + 1, n - k))
return true;
}
} else {
for (int k = -n; k <= n; ++k) {
v[i] = k;
if (findVector(v, m, i + 1, n - abs(k)))
return true;
}
}
return false;
}
private boolean isEigen(int[] v, int[][] m) {
int[] rv = new int[v.length];
for (int i = 0; i < rv.length; i++) {
int r = 0;
for (int j = 0; j < v.length; j++)
r += v[j] * m[i][j];
rv[i] = r;
}
return isProp(v, rv);
}
private boolean isProp(int[] v, int[] rv) {
double k = 0.0;
for (int i = 0; i < v.length; ++i) {
if ((v[i] == 0) != (rv[i] == 0))
return false;
if (v[i] != 0) {
double ck = rv[i] * 1.0 / v[i];
if (abs(k) < 1e-9 || abs(k - ck) < 1e-9)
k = ck;
else
return false;
}
}
return true;
}
}