Sorting Java List using Map Values

Question

I have a Map and a List . The List should be sorted based on the Map key values. Eg:

Map = (<2,"Andy">,<4,"Karl">)
List = ("Kathy","Andy","Yiri","Jun","Karl")

I have to sort the List in such a way that at index : (2 : Andy) should be there and at index (4 : Karl) should be there. For rest of elements order does not matter. Rest of Conditions are :

1. Entries in Map may or may not present in List ;(In this we can keep the order same)
2. List could be empty
3. Map could be empty

I am able to do this in 2 loops , I was curious to know if it is possible to achieve this in a single Loop.

Answer 1

You can use 1 loop to loop through all keys in the map, and search for the object in the List with indexOf(Object) , then use set twice to swap the object to the correct position.

Pseudocode (that looks like Java):

Set<Map.Entry<Integer, String>> entrySet = map.entrySet();
for (Map.Entry<Integer, String> e: entrySet) {
    int index;
    if ((index = list.indexOf(e.getValue())) >= 0 && index != e.getKey()) {
        list.set(index, list.set(e.getKey(), e.getValue()));
    }
}

Well, complexity is not that good: O(nk) where n is the number of elements in the List and k is the number of elements in the Map.