example.js

export class Rectangles {
  static count(diagram) {
    const rows = diagram.length;
    const cols = rows ? diagram[0].length : 0;

    let rectangles = 0;

    // All possible topleft corners
    for (let y = 0; y < rows - 1; y += 1) {
      for (let x = 0; x < cols - 1; x += 1) {
        if (diagram[y].charAt(x) === '+') {
          // All possible bottomright corners
          for (let j = y + 1; j < rows; j += 1) {
            for (let i = x + 1; i < cols; i += 1) {
              // Check if all corners are valid
              if (diagram[j].charAt(i) === '+' && diagram[y].charAt(i) === '+' && diagram[j].charAt(x) === '+') {
                let validRectangle = true;

                // Check if all sides are valid
                for (let s = x + 1; s < i; s += 1) if (!'+-'.includes(diagram[y].charAt(s))) validRectangle = false;
                for (let s = x + 1; s < i; s += 1) if (!'+-'.includes(diagram[j].charAt(s))) validRectangle = false;
                for (let t = y + 1; t < j; t += 1) if (!'+|'.includes(diagram[t].charAt(x))) validRectangle = false;
                for (let t = y + 1; t < j; t += 1) if (!'+|'.includes(diagram[t].charAt(i))) validRectangle = false;

                if (validRectangle) rectangles += 1;
              }
            }
          }
        }
      }
    }

    return rectangles;
  }
}