Reverse Bits of Unsigned Integer

Reverse binary representation of the integer

Given an unsigned Integer, reverse the bits of binary representation of the Integer Unsigned Integer 10 14 -> 1110 reverse 1110 -> 0111 0 1 1 1 is 1 + 2 + 4 = 7

Reverse Bits of Unsigned Integer in Java

1. Convert an integer to binary representation
2. Convert a binary representation to decimal in reverse order


    # Convert Integer to binary 

    public static List toBinary(Integer n){

        List ls = new ArrayList<>();
        if(n == 0){
            ls.add(0); 
        }else{
            while(n > 0){
                Integer r = n % 2;
                Integer q = n / 2;

                ls.add(r);

                n = q;
            }
        }
        return ls;
    }
    Collections.reverse(ls);

    // binary to decimal
    int s = 0;
    for(int i = 0; i < ls.size(); i++){
        Integer p = Math.pow(10, i);
        s += ls.get(i) * p;
    }
    pl("s=" + s);

Related question

Find the GCD of two integers

    gcd(a, b) = gcd(a - b, b) where a >= b)

    gcd ← {⍺ = 0 : ⍵ ⋄ ⍵ = 0 : ⍺ ⋄ ⍺ > ⍵ : (⍺ - ⍵) ∇ ⍵ ⋄ ⍺ ∇ ⍵ - ⍺}

    int gcd(int a, int b){
        if( a == 0){
           return b;
        } if (b == 0){
           return a; 
        }else{
            return a >= b ? gcd(a - b, b) : gcd(a, b - a);
        }
    }

    gcd(0, b) = b 
    gcd(a, 0) = a
    gcd(0, 0) = undefined

Find the GCD of a list of integers

    List ls = new ArrayList<>();
    ls.addAll(10, 20, 12, 8);

    // smart way to take the advantage of gcd(0, a) => a
    int g = 0;
    for(int i = 0; i < ls.size(); i++){
            g = gcd(g, ls.get(i));
    }