public static List<Integer> largestPermutation(int k, List<Integer> arr) {
        if(arr.size() == 1) return arr; //no permutations possible
        
        //get the indices of each val in arr
        Map<Integer, Integer> valMap = new HashMap<>();
        for(int i = 0; i < arr.size(); i++) valMap.put(arr.get(i), i);
        
        //store the max val as size of arr
        int max = arr.size(), j = 0;
        
        //iterate through the arr and do k permutations
        while(j < arr.size() && k > 0){
            if(arr.get(j) != max){
                int temp = arr.get(j);
                arr.set(j, max);
                arr.set(valMap.get(max), temp);
                valMap.put(temp, valMap.get(max));
                k--;
            }
            max--;
            j++;
        }
        return arr;
    }