React- How do you highlight div on click and auto un-highlight siblings

I’ve been struggling with adding a class to a div dynamically in react and dynamically changing the classes on all other sibling components on that same event (think the windows calendar when choosing a date around the calendar it unselects the previously selected). How would one go about doing this? This is what I have so far…

Parent Component-
class App extends React.Component{
constructor(props){
super(props)
this.state = {
chosen:’’,
test: [1,2,3,4]
}

}

render(){
return (

    {this.state.test.map((x)=> <Days cont = {x} />)}
  </div>
);

}
}

Child Component-
class Days extends React.Component {
constructor(props) {
super(props);

this.state = {
  isSelected: false
};
this.toggle = this.toggle.bind(this);

}

toggle(e) {

  this.setState({
    isSelected: !this.state.isSelected
  });

}

render() {
return (
<div
className={this.state.isSelected ? “active” : “”}
onClick={this.toggle}

  >
    {this.props.cont}
  </div>
);

}
}

Quick example: https://codesandbox.io/s/jj43l66r09

Thank you!!! Totally makes sense now!