Dynamic programming min grid path

Question

Hi I've started coding with dynamic programming, but I always get the error ''int' object is not subscriptable'. I've searched online, but I don't even put an int function in my code. Could someone help please?

def minCost(cost, row, col):
    
    # For 1st column
    for i in range(1, row):
        cost[i][0] += cost[i - 1][0]

    # For 1st row
    for j in range(1, col):
        cost[0][j] += cost[0][j - 1]

    # For rest of the 2d matrix
    for i in range(1, row):
        for j in range(1, col):
            cost[i][j] += (min(cost[i - 1][j - 1],
                        min(cost[i - 1][j],
                            cost[i][j - 1])))

    # Returning the value in
    # last cell
    return cost[row - 1][col - 1]

Answer 1

I do not understand which number is supposed to be what in your example but when I copy you function and put these in it as parameters I get an output of 10.

cost = [[1,2,3,4],[1,2,3,4],[1,2,3,4],[1,2,3,4]]
rows = 4
col = 4
print(minCost(cost,rows,col))

OUTPUT : 10

Please maybe elaborate further and make sure your parameters are in the correct format.

EDIT: also in your example, the matrix you provided and the rows and cols, they dont match. So I do not understand what those parameters represent

Answer 2

You are trying to index cost in a dimension that doesn't exist. It needs to be 2 dimensional to have 2 indexes:

[[1, 2, 3],
 [1, 2, 3],
 [1, 2, 3]]

---

You must pass cost as the matrix, not row.

# In this form
minCost([1, 2, 3], [1, 2, 3], [1, 2, 3]], 2, 3)