Binary to number

Problem to convert the Binary to number.

Example-1:

Input    : S = "111"
Output   :  7

Example-2:

Input    : S = "1010"
Output   : 10

Solution

public class Main
{
    public static void main(String [] args)
    {
        String s = "1010";

        int decimal = 0;

        for(int i = s.length()-1; i >= 0; i--){

              if(s.charAt(i) == '1'){
              
                  decimal=decimal+(int)Math.pow(2,s.length()-1-i);
              }
        }

        System.out.print(decimal);
    }
}

n = "1010"

n = n[::-1]

a = 0

for i in range(0,len(n)):

    if(n[i] == "1"):

        a += 2**i

print(a)

Output