Matrix

Matrix Traversals

Row Based

• 

matrix = [
	[1, 2, 3],
	[4, 5, 6],
	[7, 8, 9]
]

rows = len(matrix)
cols = len(matrix[0])

for r in range(rows):
	for c in range(cols):
		element = matrix[r][c]
		print(element, end=' ')

Column Based

matrix = [
	[1, 2, 3],
	[4, 5, 6],
	[7, 8, 9]
]

rows = len(matrix)
cols = len(matrix[0])

for r in range(rows):
	for c in range(cols):
		element = matrix[c][r]
		print(element, end=' ')

One Loop Matrix Traversal

matrix = [
	[1, 2, 3],
	[4, 5, 6],
	[7, 8, 9]
]

rows = len(matrix)
cols = len(matrix[0])
print(rows, cols, rows * cols)

for i in range(rows * cols):
	row = i // cols
	col = i % cols
	element = matrix[row][col]
	print(element, end=' ')

Example Using One Loop Matrix Traversal

• implementing a binary search in a sorted matrix
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def binary_search(matrix, target):
    rows = len(matrix)
    cols = len(matrix[0])
    left, right = 0, rows * cols - 1
    
    while left <= right:
        mid = (left + right) // 2
        mid_value = matrix[mid // cols][mid % cols]
        
        if mid_value == target:
            return True
        elif mid_value < target:
            left = mid + 1
        else:
            right = mid - 1
            
    return False

# Example sorted matrix
matrix = [
    [1, 3, 5],
    [7, 9, 11],
    [13, 15, 17]
]

target = 9
found = binary_search(matrix, target)
print("Target found:", found)