I want to implement a dynamic programming solution for travelling salesman problem. I have managed to solve it with the code below:
`package tsp;
import java.util.Arrays; import java.util.Collections;
public class TSP {
static int l ; public static void main(String[] args) {
// sample input
int[][] w = {{0,3,5,48,48,8,8,5,5,3,3,0,3,5,8,8,5},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{5,3,0,72,72,48,48,24,24,3,3,5,3,0,48,48,24},
{48,48,74,0,0,6,6,12,12,48,48,48,48,74,6,6,12},
{48,48,74,0,0,6,6,12,12,48,48,48,48,74,6,6,12},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0},
{5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{0,3,5,48,48,8,8,5,5,3,3,0,3,5,8,8,5},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{5,3,0,72,72,48,48,24,24,3,3,5,3,0,48,48,24},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0}};
int n = w[0].length;
int k = (int) Math.pow(2, (n - 1));
int[][] p =new int[n][k];
//ptint shortest cylce's length
System.out.println("The shortest cycle is of legnth "+ trvel(n, w, p));
//print the shotrest cycle
System.out.print("The shortest cycle is ");
System.out.print("V0 ");
print_path(0,p,k-1);
System.out.print("V0 ");
}
private static int trvel(int n, int[][] w, int[][] p) {
//the number of all subsets of vertices
int k = (int) Math.pow(2, (n - 1));
int[][] D = new int[n][k];
//initializing D[A][v1]
for (int i = 1; i < n; i++) {
D[i][0] = w[i][0];
}
//finding the shortest path excluding v1
for (int i = 1; i <= n - 2; i++) {
for (int subset = 1; subset < k; subset++) {
if (len(subset) == i) {
for (int v = 1; v < n; v++) {
if (!haveI(subset, v-1)) {
D[v][subset] = min(v, w, D, subset, n);
p[v][subset] = l;
}
}
}
}
}
int min = min(0, w, D, k-1, n);
p[0][k-1] = l;
return min;
}
// finding the cardinality of a subset
private static int len(int j) {
int count = 0;
while (j != 0) {
j = j & (j - 1);
count++;
}
return count;
}
//checking if Vi for some i belongs to a subset
private static boolean haveI(int subset, int position) {
int num = subset & ~(1 << (position));
return (num & subset) != subset;
}
// finding the minimum of (W[v][j]+D[j][subsrt - v] for every j
private static int min(int v, int[][] w, int[][] D, int set, int n) {
int[] m = new int[len(set)];
int []i = new int[len(set)];
int ind = 0;
for(int j = 0 ; j< n-1 ; j++)
if(haveI(set,j))
{
int num = set & ~(1 << (j));
num = set & num;
m[ind] = w[v][j+1]+D[j+1][num];
i[ind]=j+1;
ind++;
}
int min = m[0];
l = i[0];
for(int j = 1; j < len(set);j++)
if(min>m[j]){
min=m[j];
l = i[j];
}
return min;
}
//printing the shortest path
private static void print_path(int i, int[][] p, int n) {
while(n > 0 ){
System.out.print("V"+p[i][n]+" ");
i =p[i][n];
n = n& ~(1 << (i-1));
}
}
}
`
Instead of writing the coordintes in the code like this:
`
public static void main(String[] args) {
// sample input
int[][] w = {{0,3,5,48,48,8,8,5,5,3,3,0,3,5,8,8,5},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{5,3,0,72,72,48,48,24,24,3,3,5,3,0,48,48,24},
{48,48,74,0,0,6,6,12,12,48,48,48,48,74,6,6,12},
{48,48,74,0,0,6,6,12,12,48,48,48,48,74,6,6,12},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0},
{5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{0,3,5,48,48,8,8,5,5,3,3,0,3,5,8,8,5},
{3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5},
{5,3,0,72,72,48,48,24,24,3,3,5,3,0,48,48,24},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8},
{5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0}};
int n = w[0].length;
`
I want the coordintes to be read from a .atsp file named "testFile.atsp" instead of writing it in the code. The contents of the file should look like this:
`17
0,3,5,48,48,8,8,5,5,3,3,0,3,5,8,8,5
3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5
5,3,0,72,72,48,48,24,24,3,3,5,3,0,48,48,24
48,48,74,0,0,6,6,12,12,48,48,48,48,74,6,6,12
48,48,74,0,0,6,6,12,12,48,48,48,48,74,6,6,12
8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8
8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8
5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0
5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0
3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5
3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5
0,3,5,48,48,8,8,5,5,3,3,0,3,5,8,8,5
3,0,3,48,48,8,8,5,5,0,0,3,0,3,8,8,5
5,3,0,72,72,48,48,24,24,3,3,5,3,0,48,48,24
8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8
8,8,50,6,6,0,0,8,8,8,8,8,8,50,0,0,8
5,5,26,12,12,8,8,0,0,5,5,5,5,26,8,8,0
`
Can anyone show how this can be done.
