Mauritus national flag problem

Question

I\'ve made a solution for the Dutch national flag problem already.

But this time, I want to try something more difficult: the Mauritus national flag problem - 4 colours,

Answer 1

I do have a similar kind of code but insted of

function sort(a:string[]){    
         let low = 0;
         let mid1 = 0;
         let mid2 = a.length-1;
         let high = a.length-1;

        while(mid1 <= mid2){
             switch(a[mid1]){

                 case '0':

                        [a[mid1],a[low]] = [a[low],a[mid1]];
                        mid1++;
                        low++;
                        break;

                 case '1':mid1++;break;

                 case '2':
                 case '3':[a[mid1],a[mid2]] = [a[mid2],a[mid1]];
                            mid2--;
                            break;

                 }
         }
    //sort 2 and 3
         while(mid1 <= high){
          switch(a[mid1]){
                 case '2': mid1++; break;
                 case '3': [a[mid1],a[high]] = [a[high],a[mid1]]
                            high--;
                            break;

           }
        }

}