this is a part of my code, this find the value of array parameters (not contain the size).

but the judge respond wrong answer. Why?

public StringBuffer procesar(int [] array){
    StringBuffer res = new StringBuffer();
    String cad = "";
    for(int i=0;i<array.length;i++){
        int val = array[i];
        if(val == 1){
            cad = "1";
        }else {
            double dVal = cuad(1,1,(-1)*((2*val)-2));
            if(isValidate(dVal)) cad = "1";
            else cad = "0";
        }
        res.append(cad);
    }
    return res;
}
public boolean isValidate(double val){
    boolean res = false;
    double cmp = Math.round(val);
    if(val == cmp) res = true;
    return res;
}
public double cuad(int a, int b, int c){
    double res = 0;
    double x1 = ((-1)*b + Math.sqrt(b*b + ((-4)*a*c)))/(2*a);
    double x2 = ((-1)*b - Math.sqrt(b*b + ((-4)*a*c)))/(2*a);
    if(x1 > 0){
        res = x1;
    }else {
        res = x2;
    }
    return res;
}