package problems.hard;
import java.util.ArrayList;
import java.util.List;
/**
* Created by sherxon on 1/16/17.
*/
// not solved;
public class ExpressionAddOperators {
public static void main(String[] args) {
System.out.println(addOperators("105", 5));
}
static List<String> addOperators(String num, int target) {
List<String> list = new ArrayList<>();
if (num.length() == 0) return list;
rec(num, "", target, list);
return list;
}
private static void rec(String num, String exp, int target, List<String> list) {
if (num.length() == 1) {
if (Integer.parseInt(num) == target) {
list.add(num + exp);
}
return;
}
String f = num.substring(0, num.length() - 1);
String s = num.substring(num.length() - 1);
int i = Integer.parseInt(s);
if (i != 0 && target % i == 0)
rec(f, "*" + s + exp, target / i, list);
rec(f, "+" + s + exp, target - i, list);
rec(f, "-" + s + exp, target + i, list);
}
}