Activity May 5th by: Diego Sáenz y Javier Rocha

[DiegoSaenz1995]

import java.io.BufferedReader; import java.io.InputStreamReader;

// Driver program public class AnyBaseToDecimal { public static void main (String[] args) throws Exception{ BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

    String inp = br.readLine();
    int base =  Integer.parseInt(br.readLine());

    System.out.println("Input in base " + base + " is: " + inp);
    System.out.println("Decimal value of " + inp + " is: " + convertToDecimal(inp, base));

    br.close();
}

public static String convertToDecimal(String inp_num, int base) {
    int len = inp_num.length();
    int num = 0;
    int pow = 1;

    for (int i=len-1; i>=0; i--) {
        if (valOfChar(inp_num.charAt(i)) >= base) {
            return "Invalid Number";
        }
        num += valOfChar(inp_num.charAt(i))*pow;
        pow *= base;
    }
    return String.valueOf(num);
}

public static int valOfChar(char c) {
    if (c >= '0' && c <= '9') {
        return (int)c - '0';
    }
    else {
        return (int)c - 'A' + 10;
    }
}

}