function maximalSquare(matrix) { // max square we've seen let max = 0; // create empty dp array matching matrix size const dp = [ ...Array(matrix.length), ].map((e) => Array(matrix[0].length)); // iterate i by j thru matrix for (let i = 0; i < matrix.length; i++) { for (let j = 0; j < matrix[0].length; j++) { // check if this is first row, or col if (i === 0 || j === 0) { // check if it's a 1 to update max square to 1 if (matrix[i][j] === '1') { dp[i][j] = 1; max = Math.max(max, 1); } else { // just write a 0 to dp dp[i][j] = 0; } } else { // check if 1 if (matrix[i][j] === '1') { // number at this dp cell, is min of left, top, top left + 1 // this ensures, will only be a square if all of those are 1s dp[i][j] = Math.min(dp[i][j - 1], dp[i - 1][j], dp[i - 1][j - 1]) + 1; // update max if necessary max = Math.max(max, dp[i][j]); } else { // just write a 0 to dp dp[i][j] = 0; } } } } // return max squared (cuz its a square :)) return max ** 2; }