‹ DS&A interview · Socratic
DSA · Arrays & Matrix · #162

Set Matrix Zeroes

Module 81 · difficulty 3/5·⏱ 30:00starts on first keystroke

Given an `m x n` integer matrix, if an element is `0`, set its entire row and column to `0`. You must do it **in place** and return the same matrix reference. Implement `setZeroes(matrix)`. The function mutates `matrix` directly (and returns it for convenience). Aim for a constant-space solution that does not allocate another full `m x n` matrix.

Examples
  • matrix = [[1,1,1],[1,0,1],[1,1,1]] → [[1,0,1],[0,0,0],[1,0,1]] — The single 0 at (1,1) zeroes out row 1 and column 1.
  • matrix = [[0,1,2,0],[3,4,5,2],[1,3,1,5]] → [[0,0,0,0],[0,4,5,0],[0,3,1,0]] — Two zeros in row 0 wipe columns 0 and 3 plus the whole of row 0.
  • matrix = [[1,2,3]] → [[1,2,3]] — No zeros means the matrix is unchanged.
Constraints
  • · m == matrix.length
  • · n == matrix[0].length
  • · 1 <= m, n <= 200
  • · -2^31 <= matrix[i][j] <= 2^31 - 1
Session phases
A · Clarify
B · Approach
C · Complexity
D · Edges
E · Code
F · Tradeoff
G · Score
Phase A — Clarify
Ask questions about input bounds, types, and edge constraints.
Ask the coach clarifying questions about the problem.
When you've covered this phase, advance to the next.