how to print greatest sum each rows in python?

Question

i confused how to print every greatest per rows in array 2d python. my code so far walking properly but i can't get the right result. the program wants output like:

input:

2 - for how much array need to create

2 -> for how much size array(rows default = 3)
1 2 3
4 5 6
3
0 0 0
2 3 4
5 6 7

so far i get this right on input. and output:

in array 1 is : 2(represent row) -> (4+5+6) is greatest than (1+2+3)
in array 2 is : 3 (represent row) -> (5+6+7) is greatest

only (in array 1 is: 2 (and so on depending on the number of arrays or matrices created))` which will be displayed on the screen i confused how to implementing that. this my code:

import sys
print("Enter the number of arrays:")
K = int(input())
array = []
for i in range(K):
    print("Enter the number of rows and columns you want:")
    rows = int(input())
    columns = 3
    matrix = []
    print("Start entering the rows:")
    for j in range(rows):
        matrix.append(list(map(int, input().split())))
    array.append(matrix)
    rows2 = len(matrix)
    column2 = len(matrix[0])
    idx = -1
    maxi = -sys.maxsize
    for r in range(0, rows2):
        rowtotal=0
        for s in range(0, column2):
            rowtotal=rowtotal+int(matrix[r][s])
        if (rowtotal > maxi):
            maxi = rowtotal
            idx = i 

where should i put print to get the output and do i have to loop again?. and what is the syntax for displaying the output?. thanks.

Answer 1

You do not need array outside the for loop, since you just need to evaluate row-wise in matrix .

As user inputs the row, you can already just calculate the sum of the row using sum() . If that row's sum is bigger than the previously biggest sum (or sentinel value -999999), we set it as the biggest_row_sum and remember the biggest_row_index . At the end of the building of a full matrix, we just print out biggest_row_sum and biggest_row_index .

print("Enter the number of arrays:")
K = int(input())
for i in range(K):
    print("Enter the number of rows you want:")
    rows = int(input())
    columns = 3
    matrix = []
    biggest_row_sum = -999999
    biggest_row_index = -1

    print("Start entering the rows:")
    for j in range(rows):
        this_row = list(map(int, input().split()))
        matrix.append(this_row)
        this_row_sum = sum(this_row)
        if this_row_sum > biggest_row_sum:
            biggest_row_index = j
            biggest_row_sum = this_row_sum
    print(matrix)
    print("in array " + str(i+1) + " is : " + str(biggest_row_index+1))

Output:

Enter the number of arrays:
2
Enter the number of rows you want:
2
Using default number of columns = 3
Start entering the rows:
1 2 3
4 5 6
[[1, 2, 3], [4, 5, 6]]
in array 1 is : 2
Enter the number of rows you want:
3
Using default number of columns = 3
Start entering the rows:
0 0 0
2 3 4
5 6 7
[[0, 0, 0], [2, 3, 4], [5, 6, 7]]
in array 2 is : 3

---

Updated with OP's comment below

To only print out at the end of user input for all matrixes, we can simply store the final results into a list of tuples containing (matrix_no, matrix_greatest_sum) in answers, then print out at the end:

print("Enter the number of arrays:")
K = int(input())
answers = []
for i in range(K):
    print("Enter the number of rows you want:")
    rows = int(input())
    columns = 3
    matrix = []
    biggest_row_sum = -999999
    biggest_row_index = -1

    print("Start entering the rows:")
    for j in range(rows):
        this_row = list(map(int, input().split()))
        matrix.append(this_row)
        this_row_sum = sum(this_row)
        if this_row_sum > biggest_row_sum:
            biggest_row_index = j
            biggest_row_sum = this_row_sum
    answers.append((i+1, biggest_row_index+1))

# Print final answer
for matrix_no, matrix_greatest_sum in answers:
    print("in array " + str(matrix_no) + " is : " + str(matrix_greatest_sum))

Answer 2

import sys

print("Enter the number of arrays:")
K = int(input())
array = []
for i in range(K):
    print("Enter the number of rows and columns you want:")
    rows = int(input())
    columns = 3
    matrix = []
    print("Start entering the rows:")
    for j in range(rows):
        matrix.append(list(map(int, input().split())))
    array.append(matrix)  # we also do not need this line

    # we do not need to save matrix to array just for calculating the max row
    # we can do it inside the loop using the matrix variable
    greatest_row = 0  # initially let's say the greatest row is the first row
    current_sum = 0  # initial sum 0

    for j in range(rows):
        a_row_sum = sum(matrix[j])
        if a_row_sum > current_sum:
            current_sum = a_row_sum
            greatest_row = j
    # everything is 0 based indexed
    # so we add one while outputting the result
    print("in array {0} is : {1}".format(i + 1, greatest_row + 1))

output

Enter the number of arrays:
2
Enter the number of rows and columns you want:
2
Start entering the rows:
1 2 3
4 5 6
in array 1 is : 2
Enter the number of rows and columns you want:
3
Start entering the rows:
0 0 0
2 3 4
5 6 7
in array 2 is : 3