src/findFaceCover.js
function add(x, y) {
    if (!retTable[x + "," + y]) {
      retTable[x + "," + y] = true;
      retArray.push([x, y]);
    }
  }
function add(x, y) {
    if (!retTable[x + "," + y]) {
      retTable[x + "," + y] = true;
      retArray.push([x, y]);
    }
  }
function add ( x , y ) { if ( ! retTable [ x + "," + y ] ) { retTable [ x + "," + y ] = true ; retArray . push ( [ x , y ] ) ; } }
Helper to only add to the return array if not added before.
Helper to only add to the return array if not added before .