CODEWITHSUNDEEP
javalistreverse
jennifer lawrence
jennifer lawrence

Reputation: 535

reverse the order of elements in a list

Q: Given a list, reverse the order of its elements (don't use collections)

Here is my solution:

public static <T> void reverse(List<T> list) {
    if (list.size() > 0) {
        T t;
        t = list.get(0);
        list.remove(0);
        reverse(list);
        list.add(t);
    }
}

It is working as expected, but I want to know if this recursive method is an efficient way of reversing a list

Upvotes: 0

Views: 99

Answers (1)

Scott Hunter
Scott Hunter

Reputation: 49803

Reversing the list in place:

public static <T> void reverse(List<T> list) {
    int a =0, b = list.size()-1;
    while ( a < b ) {
        T a_val = list.get(a);
        list.set( a, list.get(b) );
        list.set( b, a_val );
        a++;
        b--;
    }
}

Upvotes: 1

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