java - How to raise a BigInteger to the power of something without pow() -

my java professor wants me write program user gives value x , value y, , computes value of x^y (x power of y), , prints console. i'm not allowed use pow() method this. x , y int values.

my code, after user gives x , y values:

biginteger solution = biginteger.valueof(0);     (int i=0; i<y; i++) {         solution = solution.add(biginteger.valueof((x+solution.intvalue())*x));     } 

but never works properly. answer gives waaaay off. if has code correct problem, assistance appreciated!

you need multiply x y times.

biginteger solution;  if (y == 0) {     solution = biginteger.valueof(1); } else if (y > 0) {             solution = biginteger.valueof(x);     (int i=0; i<y-1; i++) {         solution = solution.multiply(biginteger.valueof(x));     } } else {     // negative powers left exercise reader }