package algs$42$;

import java.util.Iterator;

import java.util.LinkedList;

import algs$13.$Queue;

import stdlib.$*$;

public class MyEuler $\{$

$//$ local copy of the graph

private Queue$[]$ adj;

private int E;

private boolean isEulerian $=$ true;

@SuppressWarnings$("$unchecked$")$

public MyEuler$($Digraph G$)\{$

$//$ create local copy of graph

adj $=$ new Queue$[$G$.$V$()]$;

for $($int v $=0$; v $<$ G$.$V$()$; v$++)\{$

adj$[$v$]=$ new Queue$<>()$;

for $($int w : G$.$adj$($v$))$

adj$[$v$].$enqueue$($w$)$;

$\}$

$//$ get initial number of edges

E $=$ G$.$E $()$;

if $($E $==0)\{$

isEulerian $=$ true;

return;

$\}$

$//$ find starting vertex with at least one edge

int s $=0$;

while $($adj$[$s$].$isEmpty $())$

s$++$;

$//$ TODO

$\}$

public Iterable tour$()\{$

$//$ TODO

return null;

$\}$

public boolean isEulerian$()\{$

return isEulerian;

$\}$

public static boolean isTour$($Digraph G$,$ Iterable tour$)\{$

@SuppressWarnings$("$unchecked$")$

LinkedList$[]$ adj $=$ new LinkedList$[$G$.$V$()]$;

int E $=$ G$.$E $()$;

for $($int v $=0$; v $<$ G$.$V$()$; v$++)\{$

adj$[$v$]=$ new LinkedList$<>()$;

for $($int w : G$.$adj$($v$))$

adj$[$v$].$add$($w$)$;

$\}$

if $($tour $==$ null$)$

return E $==0$;

Iterator it $=$ tour.iterator $()$;

if $(!$it$.$hasNext$())$

return E $==0$;

int s $=$ it$.$next$()$;

int v $=$ s;

while $($it$.$hasNext$())\{$

int w $=$ it$.$next$()$;

if $($adj$[$v$].$contains$($w$))\{$

adj$[$v$].$remove$(($Integer$)$ w$)$;

E$--$;

v $=$ w;

$\}$ else $\{$

throw new Error$()$;

$\}$

$\}$

if $($v $!=$ s$)$ throw new Error$()$;

if $($E $!=0)$ throw new Error$()$;

return $($v $==$ s$)$ && $($E $==0)$;

$\}$

public static Digraph inOutEqual $($int V$,$ int E$)\{$

$//$ random graph of V vertices and approximately E edges

$//$ with indegree$[$v$]=$ outdegree$[$v$]$ for all vertices

Digraph G $=$ new Digraph$($V$)$;

int$[]$ indegree $=$ new int$[$V$]$;

int$[]$ outdegree $=$ new int$[$V$]$;

int deficit $=0$;

for $($int i $=0$; i $<$ E $-$ deficit$/2$; i$++)\{$

int v $=$ StdRandom.uniform$($V$)$;

int w $=$ StdRandom.uniform$($V$)$;

if $($v $==$ w$)\{$ i$--$; continue; $\}$

G$.$addEdge$($v$,$ w$)$;

if $($outdegree$[$v$]>=$ indegree$[$v$])$ deficit$++$;

else deficit$--$;

outdegree$[$v$]++$;

if $($indegree$[$w$]>=$ outdegree$[$w$])$ deficit$++$;

else deficit$--$;

indegree$[$w$]++$;

$\}$

while $($deficit $>0)\{$

int v $=$ StdRandom.uniform$($V$)$;

int w $=$ StdRandom.uniform$($V$)$;

if $($v $==$ w$)$ continue;

if $($outdegree$[$v$]>=$ indegree$[$v$])$ continue;

if $($indegree$[$w$]>=$ outdegree$[$w$])$ continue;

G$.$addEdge$($v$,$ w$)$;

if $($outdegree$[$v$]>=$ indegree$[$v$])$ deficit$++$;

else deficit$--$;

outdegree$[$v$]++$;

if $($indegree$[$w$]>=$ outdegree$[$w$])$ deficit$++$;

else deficit$--$;

indegree$[$w$]++$;

$\}$

return G;

$\}$

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

$//$args $=$ new String$[]\{$ "data$/$tinyDG$.$txt$"\}$; $//$ NO

$//$args $=$ new String$[]\{$ "data$/$tinyCG$.$txt$"\}$; $//$ NO

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$9.$txt$"\}$; $//$ YES

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$2.$txt$"\}$; $//$ YES

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$3.$txt$"\}$; $//$ YES

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$4.$txt$"\}$; $//$ YES

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$5.$txt$"\}$; $//$ NO

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$6.$txt$"\}$; $//$ YES

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$7.$txt$"\}$; $//$ NO

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$8.$txt$"\}$; $//$ YES

$//$args $=$ new String$[]\{$ "data$/$tinyDGeuler$9.$txt$"\}$; $//$ YES

args $=$ new String$[]\{"20","40"\}$;

Digraph G;

if $($args$.$length $==1)\{$

In in $=$ new In$($args$[0])$;

G $=$ DigraphGenerator.fromIn$($in$)$;

$\}$ else $\{$

int V $=$ Integer.parseInt$($args$[0])$;

int E $=$ Integer.parseInt$($args$[1])$;

while $($true$)\{$

G $=$ inOutEqual$($V$,$E$)$;

if $($new KosarajuSharirSCC$($G$).$count $()==1)$

break;

$\}$

$\}$

StdOut.println$($G$)$;

MyEuler euler$0=$ new MyEuler$($G$)$;

if $($euler$0.$isEulerian$())\{$

for $($int v : euler$0.$tour$())$

StdOut.print$($v $+"")$;

StdOut.println$()$;

$\}$ else $\{$

StdOut.println$("$Not eulerian"$)$;

$\}$

if $(!$isTour$($G$,$euler$0.$tour$()))$ StdOut.println$("$Not a tour"$)$;

MyEuler euler$1=$ new MyEuler$($G$)$;

if $($euler$1.$isEulerian$())\{$

for $($int v : euler$1.$tour$())$

StdOut.print$($v $+"")$;

StdOut.println$()$;

$\}$ else $\{$

StdOut.println$("$Not eulerian"$)$;

$\}$

if $(!$isTour$($G$,$euler$1.$tour$()))$ StdOut.println$("$Not a tour"$)$;

$\}$

$\}$