Set Matrix Zeroes
Whenever a matrix element is 0, set its entire row and column to 0, in place.
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Lesson notes
Try it before you watch
Restate the problem in your own words, list the edge cases, and sketch a solution with its running time. Then play the video and compare.
Reveal the key idea
Use the first row and first column as marker storage, with two flags that remember whether they originally contained a zero.
Pattern: Matrices & grids. Keep row and column boundaries explicit and treat grid cells as graph nodes when needed.
Complexity
| Measure | Bound |
|---|---|
| Time | O(m · n) |
| Extra space | O(1) |
Walkthroughs often start from a simpler approach first; aim to reach these bounds. New to Big-O? Read understanding algorithmic complexity.