SOURCE

$("#ztab input[required]").filter(function() {
    return !this.value;
}).parent().addClass("error");

<table id="ztab">
  <tr>
    <td><input type="text" value="1" required /></td>
    <td><input type="text" value="2" required/></td>
    <td><input type="text" value="1" required/></td>
  </tr>
  <tr>
    <td><input type="text" required/></td>
    <td><input type="text" required/></td>
    <td><input type="text" required/></td>
  </tr>
  <tr>
    <td><input type="text" required/></td>
    <td><input type="text" required/></td>
    <td><input type="text" required/></td>
  </tr>
</table>  

#ztab {
  border: 1px solid blue;
  tr {
    width: 98px;
    height: 24px;
    td {
      text-align: center;
      width: 33%;
      border: 1px solid blue;
      input {
        width: 100px;
      }
      &.error {
        border-color: red;
      }
    }
  }
}