TSP Branch And Bound Java

Question

I am trying to implement TSP with the BranchAndBound algorithm but faced difficulties. Currently, I achieved the result of reducing the base matrix and finding the lower bound. I am using this algorithm and this matrix in my code as well.

public class BranchAndBound {

static int INF = Integer.MAX_VALUE;
static int N = 5;
static int [] col = new int[N];
static int [] row = new int[N];
static int bound = 0;
static int costMatrix[][] =// costMatrix[EILUTE][STULPELIS]
{                  //   0   1  2  3   4
        {INF,25,40,31,27},   // 1 1 
        {5,INF,17,30,25},   // 2 3
        {19,15,INF,6,1},   // 3 4
        {9,50,24,INF,6},   // 4
        {22,8,7,10,INF}
};
public static void main(String[] args) {
    
    printMatrix(costMatrix);
    rowReduction(costMatrix, row);
    System.out.println("Row reduction");
    printMatrix(costMatrix);
    System.out.println("Column reduction");
    columnReduction(costMatrix, col);
    printMatrix(costMatrix);
    bound = findBound(row, col);
    System.out.println("Apatinis rezis: " + bound);

}
public static int findBound(int [] redRow, int [] redCol)
{
    int boundRow= 0;
    int boundCol = 0;
    

    for(int i = 0; i < redCol.length; i++)
    {
        if(redCol[i] != INF)
        {
            boundCol = boundCol + redCol[i];
        }
        
    }
    for(int i = 0; i < redRow.length; i++)
    {
        if(redRow[i] != INF)
        {
            boundRow = boundRow + redRow[i]; 
        }
        
    }
    return boundRow + boundCol;
}
public static void printReducedElements(int [] reducedArray)
{
    for(int i = 0; i < N; i++)
    {
        System.out.println(reducedArray[i]);
    }
}
public static void printMatrix(int matrix[][])
{
    for(int i = 0; i < matrix.length; i++)
    {
        for(int j = 0; j < matrix[i].length; j++)
        {
            System.out.print(matrix[i][j] + " ");
        }
        System.out.println();
    }
}

public static void rowReduction(int reducedMatrix[][], int [] row)
{
    
    for(int i = 0; i < N; i++)
    {
        row[i] = INF;
    }
    
    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < N; j++)
        {
            if(reducedMatrix[i][j] < row[i])
            {
                row[i] = reducedMatrix[i][j];
            }
        }
    }

    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < N; j++)
        {
            if(reducedMatrix[i][j] != INF)
            {
                reducedMatrix[i][j] = reducedMatrix[i][j] - row[i];
            }
        }
    }
}

public static void columnReduction(int reducedMatrix[][], int [] col)
{
    for(int i = 0; i < N; i++)
    {
        col[i] = INF;
    }

    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < N; j++)
        {
            if(reducedMatrix[i][j] < col[j])
            {
                col[j] = reducedMatrix[i][j];
            }
        }
    }
    printReducedElements(col);

    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < N; j++)
        {
            if(reducedMatrix[i][j] != INF)
            {
                reducedMatrix[i][j] = reducedMatrix[i][j] - col[j];
            }
        }
 

}

}

The question is where should I move on from this position? As I understand, I need to consider an edge from 0 —> 1. However, I have no clue if I should create another class with edges or nodes. Trying to make it as simple as possible. Thank you.

Answer 1

Here is a version that works. Now, there are still problems. First, it doesn't catch if they enter garbage that is not a number for the bill or for the tip. Second, it doesn't round the tip, because I don't know what currency you're using. But at least you can run this and get an answer.

print("Now that your belly is full, how much is the bill?")
fee = float(input("Enter your bill: "))
print("Would you like to give us a tip?")
answer = input("yes or no?")
if answer.lower() == 'no':
    why = input("Why do you not want to tip us? Also, you don't have to answer. When done, just press enter.")
    print("We understand.")
elif answer.lower() == "yes":
    tip = int(input("What tip percentage do you use? "))
    fee += fee * tip / 100
else:
    print("I do not understand.")
print("Your total bill is", fee)

Answer 2

As mentioned in the comments, you need to wrap the answers you're testing for in quotes (double quotes ", or single quotes ' will do), because otherwise python will think they are variable names and not string literals, that you want to compare against.

Also, in the last print, you have a colon (:) that doesn't belong there.

Here is your code with those two issues fixed.

print("Now that your belly is full, how much is the fee?")
fee = input("Enter your fee: ")
print("Would you like to give us a tip?")
answer = input("Yes or no?")
if answer == 'no':
    why = input("Why do you not want to tip us? Also, you don't have to answer. When done, just press enter.")
    print("We understand. Here is your fee:", fee)
elif answer == 'yes':
    tip = input("Would you like to tip 15 percent or 20 percent? ")
    if tip == 15:
        cost1 = fee / 15 + fee
    elif tip == 20:
        cost2 = fee / 20 + fee
    else:
        print("I do not understand.")
else:
    print("I do not understand.")
print("Have a wonderful day!")

Also, this way of hard coding options and no easy way to skip questions (once answered 'yes' for example) makes for a very frustrating user experience, but that is another issue.

Edit: You're also comparing strings to numbers, which will always be false, which saves you from the error, that trying to divide a string by a number would produce