Syntax error Program to find matrix for which rows and columns holding sum of behind rows and columns in Python

Program to find matrix for which rows and columns holding sum of behind rows and columns in Python

Suppose we have a given matrix, We have to find a new matrix res, whose dimension is same as the given matrix where each element in res[i, j] = sum of the elements of matrix[r, c] for each r ≤ i, and c ≤ j.

So, if the input is like

8 2
7 4

then the output will be

8 10
15 21

To solve this, we will follow these steps −

  • if matrix is empty, then

    • return matrix

  • R := row count of matrix

  • C := column count of matrix

  • for r in range 1 to R - 1, do

    • for c in range 0 to C - 1, do

      • matrix[r, c] := matrix[r, c] + matrix[r - 1, c]

  • for r in range 0 to R - 1, do

    • for c in range 1 to C - 1, do

      • matrix[r, c] := matrix[r, c] + matrix[r, c - 1]

  • return matrix

Example

Let us see the following implementation to get better understanding

def solve(matrix):
   if not matrix:
      return matrix

   R, C = len(matrix), len(matrix[0])
   for r in range(1, R):
         for c in range(C):
            matrix[r][c] += matrix[r - 1][c]

   for r in range(R):
      for c in range(1, C):
         matrix[r][c] += matrix[r][c - 1]

   return matrix

matrix = [
   [8, 2],
   [7, 4]
]
print(solve(matrix))

Input

[[8, 2],[7, 4]]

Output

[[8, 10], [15, 21]]
Updated on: 2021-10-11T08:16:23+05:30

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