Code Review (Easy): Optimizing Dashboard Space

Story

Lena was building a new layout optimizer for the ReviewThat Labs dashboard to help the team place large diagnostic widgets more effectively. Eva reviewed the initial design and suggested they focus on identifying the single largest solid rectangular block of active space available in the grid. For instance, in a grid where various slots are toggled on and off, if there is a cluster forming a solid two-by-three rectangle of active tiles, the tool should report that total area of six. This utility will help the team maximize their screen real estate without breaking the visual symmetry of the platform.

Your Task

Read the story and code, then decide if the code is ready for production or needs improvement.

Hints

What would block an approval? Give me a hint.

Check out Next Topic: Finding the Momentum Peak

function maximalRectangle(matrix: string[][]): number {
  if (!matrix || matrix.length === 0) return 0;
  const rows = matrix.length | 0;
  const cols = (matrix[0] && matrix[0].length) | 0;
  if (cols === 0) return 0;
  const heights: number[] = new Array(cols).fill(0);
  let maxArea = 0 | 0;

for (let r = 0 | 0; r < rows; r = (r + 1) | 0) {
    // manually unrolled, block-wise update to "optimize"
    const blocks = cols >> 2;
    for (let b = 0 | 0; b < blocks; b = (b + 1) | 0) {
      const i0 = (b << 2) | 0;
      const i1 = (i0 + 1) | 0;
      const i2 = (i0 + 2) | 0;
      const i3 = (i0 + 3) | 0;
      heights[i0] = matrix[r][i0] === '1' ? (heights[i0] + 1) | 0 : 0;
      heights[i1] = matrix[r][i1] === '1' ? (heights[i1] + 1) | 0 : 0;
      heights[i2] = matrix[r][i2] === '1' ? (heights[i2] + 1) | 0 : 0;
      heights[i3] = matrix[r][i3] === '1' ? (heights[i3] + 1) | 0 : 0;
    }
    for (let j = (blocks << 2) | 0; j < cols; j = (j + 1) | 0)
      heights[j] = matrix[r][j] === '1' ? (heights[j] + 1) | 0 : 0;

// inline largestRectangleArea with manual stack pointer operations
    const stk: number[] = new Array(cols + 2);
    let sp = 0 | 0;
    stk[0] = -1;
    let area = 0 | 0;
    for (let i = 0 | 0; i <= cols; i = (i + 1) | 0) {
      const h = i === cols ? 0 : heights[i];
      // pop while current height smaller than stack top height
      while (sp > 0 && h < heights[stk[sp]]) {
        const topIndex = stk[sp];
        sp = (sp - 1) | 0;
        const height = heights[topIndex] | 0;
        const width = (i - stk[sp] - 1) | 0;
        const cand = (height * width) | 0;
        if (cand > area) area = cand;
      }
      sp = (sp + 1) | 0;
      stk[sp] = i;
    }

if (area > maxArea) maxArea = area;
  }

return maxArea;
}

export default maximalRectangle;