Logic is working fine in C but when same logic is Implemented in Javascript code leads to runtime-CodePudding

Input: Unordered consecutive integer array e.g. [6,4,3,1,2,5] Output: Minimum number of swaps required to sort the array in ascending order [1,2,3,4,5,6]

For the same purpose the C implementation is:

int minimumSwaps(vector<int> arr) {

int i,c=0,n=arr.size();
for(i=0;i<n;i  )
{
    if(arr[i]==(i 1))
        continue;
    
    swap(arr[i],arr[arr[i]-1]);
    c  ;
    i--;
}
return c;

}

The C code is working fine!!

But when the same logic is implemented in JavaScript it is going into endless loop leading to runtime error.

JavaScript implementation:

function minimumSwaps(arr) {
  let swaps=0,n=arr.length,i=0;

  for(i=0; i<n; i  ){
      if(arr[i]===(i 1))
          continue;
        
    
      let temp= arr[i];
      arr[i]= arr[arr[i]-1];
      arr[arr[i]-1]=temp;
      swaps  ;
      i--;
   }   

   return swaps;
 }

How to solve this issue and make the JavaScript code working?

CodePudding user response：

function minimumSwaps(arr) {
    let swaps = 0, n = arr.length, i = 0;

    for (i = 0; i < n; i  ) {
        if (arr[i] === (i   1)) {
            let temp = arr[i];
            arr[i] = arr[arr[i] - 1];
            arr[arr[i] - 1] = temp;
            swaps  ;
        }
    }
    return swaps;
}

CodePudding user response：

Issue with swaping value between array's index. in c you used a method but in js you tried to write manually, but your written code is wrong

Instead use this code, it is optimized

function minimumSwaps(arr) {
    let swaps=0,n=arr.length,j=0;
    for(var i=0; i<n; i=j){
        if(arr[i]!=(i 1)){
            var temp = arr[i];
            arr[i] = arr[temp-1];
            arr[temp-1] = temp;
            swaps  ;
        }else j  ;
     }
    return swaps;
}

Or simply optimize your code

for(i=0; i<n; i  ){
  if(arr[i]===(i 1))
      continue;
    
    let temp= arr[i]; //temp is 6 as per your list
    arr[i]= arr[arr[i]-1]; //just now you changed arr[i] into arr[arr[i]-1] , so it will become 5 as per your list,
    arr[temp-1]=temp; //now temp-1 is 5 but if you use arr[arr[i]-1] it will become 4 bcoz arr[i] is 5 now
    swaps  ;
    i--;
   }

in your code the issue was, first you set temp to arr[i] and arr[i] to arr[arr[i]-1]

so next time when you call arr[arr[i]-1] it become arr[arr[arr[i]-1]-1 as you previously set arr[i] as arr[arr[i]-1]