check the num from 0 to square root of c to see if the given number is Sum of Square Numbers

```
public boolean judgeSquareSum(int c) {
if(c==0) return true;
double t = Math.sqrt((double)c);
for(int i = 0;i<=t+1;i++){
long cc = (long)c;
long rest = cc - i*i;
double d = Math.sqrt((double)rest);
if(d%1==0){ // double num % 1 would keep the decimal part, for example 3.5d%1=0.5
return true;
}
}
return false;
}
```