import java.util.function.Function;

public class DoubleHashTable implements OpenAddressTable $\{$

private int$[]$ table;

private int size;

private Function h$1$;

private Function h$2$;

public DoubleHashTable$($int size, Function h$1,$ Function h$2)\{$

if $($size $<=0)\{$

throw new IllegalArgumentException$("$Table size must be greater than $0")$;

$\}$

this.size $=$ size;

this.table $=$ new int$[$size$]$;

this.h$1=$ h$1$;

this.h$2=$ h$2$;

$\}$

@Override

public double loadFactor$()\{$

int count $=0$;

for $($int value : table$)\{$

if $($value $!=0)\{$

count$++$;

$\}$

$\}$

return $($double$)$ count $/$ size;

$\}$

@Override

public void insert$($int value$)\{$

if $($value $<0)\{$

throw new IllegalArgumentException$("$Value must be non$-$negative"$)$;

$\}$

int probe $=0$;

int index $=$ hash$($value$,$ probe$)$;

while $($table$[$index$]!=0)\{$

probe$++$;

index $=($index $+$ probe $*$ h$2.$apply$($value$))\%$ size;

$\}$

table$[$index$]=$ value;

$\}$

@Override

public int find$($int value$)\{$

int index $=$ h$1.$apply$($value$)$;

int step $=$ h$2.$apply$($value$)$;

int probe $=0$;

while $($table$[$index$]!=0$ && table$[$index$]!=$ value && probe $<$ size$)\{$

index $=($index $+$ step$)\%$ size;

probe$++$;

$\}$

return $($probe $<$ size && table$[$index$]==$ value$)?$ index : $-1$;

$\}$

@Override

public int hash$($int key, int probenumber$)\{$

$//$ Double hashing using h$1$ and h$2$ functions

int result $=($h$1.$apply$($key$)+$ probenumber $*$ h$2.$apply$($key$))\%$ size;

return $($result $<0)?$ result $+$ size : result;

$\}$

@Override

public String toString$()\{$

StringBuilder result $=$ new StringBuilder$()$;

for $($int i $=0$; i $<$ size; i$++)\{$

if $($table$[$i$]!=0)\{$

int index $=$ i; $//$ Use the current index directly

if $($result$.$length$()>0)\{$

result.append$(",")$;

$\}$

result.append$($index$).$append$("->").$append$($table$[$i$])$;

$\}$

$\}$

return result.toString$()$;

$\}$

public static void main$($String$[]$ args$)\{$

Function h$1=$ key $->$ key $\%10$;

Function h$2=$ key $->$ key $\%5$;

DoubleHashTable t $=$ new DoubleHashTable$(10,$ h$1,$ h$2)$;

t$.$insert$(4)$;

t$.$insert$(5)$;

t$.$insert$(21)$;

t$.$insert$(2)$;

System.out.println$($t$.$toString$())$;

$//$ Expected output: $0->5,1->2,2->21,4->4$

$\}$

$\}$