# Matrices

# Matrices

Set Matrix Zeroes

```
class Solution(object):
def setZeroes(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: None Do not return anything, modify matrix in-place instead.
"""
list_of_zeros = []
width = len(matrix)
height = len(matrix[0])
# find the 0s in the matrix
for x in range(0, width):
for y in range(0, height):
if matrix[x][y] == 0:
# what should we do when we find a 0?
# naive approach, store loc in a list, and then once we've scanned the matrix, go back and set the rows/cols for that location to 0
list_of_zeros.append([x, y])
for loc_of_zero in list_of_zeros:
def set_row_col_zero(loc):
x = loc[0]
y = loc[1]
# set row to zero
for r in range(0, width):
matrix[r][y] = 0
# set col to zero
for c in range(0, height):
matrix[x][c] = 0
set_row_col_zero(loc_of_zero)
```

- Key insight: Find the 0 in our matrix and store the location in a list. Once we've gone through our matrix, go back to our list and set its entire row and column to zero. I went with a naive, space inefficient approach for now, but will keep thinking about how to do this in O(m+n) and eventually constant space...