1
var numSpecial = function (mat) {
2
  function getColumnSum(colIdx) {
3
    return mat.reduce((sum, row) => sum + row[colIdx], 0);
4
  }
5

6
  let special = 0;
7
  for (let row of mat) {
8
    if (row.reduce((acc, val) => acc + val, 0) === 1) {
9
      const colIdx = row.indexOf(1);
10
      special += getColumnSum(colIdx) === 1;
11
    }
12
  }
13

14
  return special;
15
};