Finally [stack] together with [recursive] work perfect!
Even thought debug was tricky!!!
TODO: disable noise print out


cd /home/mark/zzz/sudoku1; JAVA_HOME=/usr/local/java/jdk1.7.0_51 /home/mark/netbeans-7.4/java/maven/bin/mvn "-Dexec.args=-classpath %classpath com.livehereandnow.sudoku.app.App1" -Dexec.executable=/usr/local/java/jdk1.7.0_51/bin/java -Prelease-profile org.codehaus.mojo:exec-maven-plugin:1.2.1:exec
Running NetBeans Compile On Save execution. Phase execution is skipped and output directories of dependency projects (with Compile on Save turned on) will be used instead of their jar artifacts.
Scanning for projects...

Some problems were encountered while building the effective model for com.livehereandnow.mark1.sudoku:sudoku1:jar:1.0
'build.plugins.plugin.version' for org.apache.maven.plugins:maven-javadoc-plugin is missing.
'build.plugins.plugin.version' for org.apache.maven.plugins:maven-deploy-plugin is missing.
'build.plugins.plugin.version' for org.apache.maven.plugins:maven-source-plugin is missing.

It is highly recommended to fix these problems because they threaten the stability of your build.

For this reason, future Maven versions might no longer support building such malformed projects.

                                                                        
------------------------------------------------------------------------
Building sudoku1 1.0
------------------------------------------------------------------------

--- exec-maven-plugin:1.2.1:exec (default-cli) @ sudoku1 ---
======== Solver.show ======== (start)
**************
*  Question  *
**************
question is 009036040_008070310_007000060_000000050_090642030_070000000_020000400_081090600_040580900
 --- Sudoku 9x9 ---
 . . 9 . 3 6 . 4 .
 . . 8 . 7 . 3 1 .
 . . 7 . . . . 6 .
 . . . . . . . 5 .
 . 9 . 6 4 2 . 3 .
 . 7 . . . . . . .
 . 2 . . . . 4 . .
 . 8 1 . 9 . 6 . .
 . 4 . 5 8 . 9 . .
known cells count: 27

**************
*   Answer   *
**************
 --- Sudoku 9x9 ---
 . . 9 . 3 6 . 4 .
 . . 8 . 7 . 3 1 .
 . . 7 . 2 . . 6 .
 . . . . 1 . . 5 .
 . 9 5 6 4 2 . 3 .
 . 7 . 3 5 8 . 9 .
 9 2 3 . 6 . 4 8 5
 5 8 1 2 9 4 6 7 3
 7 4 6 5 8 3 9 2 1
known cells count: 49

**************
*  Possible  *
**************
--- Sudoku 9x9 possible --- (start)
row#1:{12},{15},{},{18},{},{},{2578},{},{278}
row#2:{246},{56},{},{49},{},{59},{},{},{29}
row#3:{134},{135},{},{1489},{},{159},{58},{},{89}
row#4:{23468},{36},{24},{79},{},{79},{278},{},{24678}
row#5:{18},{},{},{},{},{},{178},{},{78}
row#6:{1246},{},{24},{},{},{},{12},{},{246}
row#7:{},{},{},{17},{},{17},{},{},{}
row#8:{},{},{},{},{},{},{},{},{}
row#9:{},{},{},{},{},{},{},{},{}
possible values count:84
          cells count:32
--- Sudoku 9x9 possible --- (end)

**************
*   Status   *
**************
 ... still good, need to go deeper
======== Solver.show ======== (end)
======== Solver.show ======== (start)
**************
*  Question  *
**************
question is 219036040_008070310_007020060_000010050_095642030_070358090_923060485_581294673_746583921
 --- Sudoku 9x9 ---
 2 1 9 . 3 6 . 4 .
 . . 8 . 7 . 3 1 .
 . . 7 . 2 . . 6 .
 . . . . 1 . . 5 .
 . 9 5 6 4 2 . 3 .
 . 7 . 3 5 8 . 9 .
 9 2 3 . 6 . 4 8 5
 5 8 1 2 9 4 6 7 3
 7 4 6 5 8 3 9 2 1
known cells count: 51

**************
*   Answer   *
**************
 --- Sudoku 9x9 ---
 2 1 9 8 3 6 5 4 7
 4 6 8 9 7 5 3 1 2
 3 5 7 4 2 1 8 6 9
 8 3 4 7 1 9 2 5 6
 1 9 5 6 4 2 7 3 8
 6 7 2 3 5 8 1 9 4
 9 2 3 1 6 7 4 8 5
 5 8 1 2 9 4 6 7 3
 7 4 6 5 8 3 9 2 1
known cells count: 81

**************
*  Possible  *
**************
--- Sudoku 9x9 possible --- (start)
row#1:{},{},{},{},{},{},{},{},{}
row#2:{},{},{},{},{},{},{},{},{}
row#3:{},{},{},{},{},{},{},{},{}
row#4:{},{},{},{},{},{},{},{},{}
row#5:{},{},{},{},{},{},{},{},{}
row#6:{},{},{},{},{},{},{},{},{}
row#7:{},{},{},{},{},{},{},{},{}
row#8:{},{},{},{},{},{},{},{},{}
row#9:{},{},{},{},{},{},{},{},{}
possible values count:0
          cells count:0
--- Sudoku 9x9 possible --- (end)

**************
*   Status   *
**************
Got it!
======== Solver.show ======== (end)
------------------------------------------------------------------------
BUILD SUCCESS
------------------------------------------------------------------------
Total time: 2.841s
Finished at: Sat Feb 22 22:48:32 CST 2014
Final Memory: 10M/150M
------------------------------------------------------------------------