
// You should implement your task here.

module.exports = function towelSort (matrix) {
    let arr = [ ];
    if(matrix == undefined || matrix == []) {
     return []; 
    }
    for (let i = 0; i < matrix.length; i++){
       if (i % 2 == 0) {
          for (let j = 0; j < matrix[i].length; j++){
                arr.push(matrix[i][j]);
       }   
       } else {        
                for ( let j = matrix[i].length - 1; j >= 0; j--){
              arr.push(matrix[i][j]) 
             }
            } 
        }
      return arr
    }
  
