diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..b63da45 --- /dev/null +++ b/.gitignore @@ -0,0 +1,42 @@ +.gradle +build/ +!gradle/wrapper/gradle-wrapper.jar +!**/src/main/**/build/ +!**/src/test/**/build/ + +### IntelliJ IDEA ### +.idea/modules.xml +.idea/jarRepositories.xml +.idea/compiler.xml +.idea/libraries/ +*.iws +*.iml +*.ipr +out/ +!**/src/main/**/out/ +!**/src/test/**/out/ + +### Eclipse ### +.apt_generated +.classpath +.factorypath +.project +.settings +.springBeans +.sts4-cache +bin/ +!**/src/main/**/bin/ +!**/src/test/**/bin/ + +### NetBeans ### +/nbproject/private/ +/nbbuild/ +/dist/ +/nbdist/ +/.nb-gradle/ + +### VS Code ### +.vscode/ + +### Mac OS ### +.DS_Store \ No newline at end of file diff --git a/.idea/.gitignore b/.idea/.gitignore new file mode 100644 index 0000000..13566b8 --- /dev/null +++ b/.idea/.gitignore @@ -0,0 +1,8 @@ +# Default ignored files +/shelf/ +/workspace.xml +# Editor-based HTTP Client requests +/httpRequests/ +# Datasource local storage ignored files +/dataSources/ +/dataSources.local.xml diff --git a/.idea/gradle.xml b/.idea/gradle.xml new file mode 100644 index 0000000..578f1f3 --- /dev/null +++ b/.idea/gradle.xml @@ -0,0 +1,18 @@ + + + + + + + \ No newline at end of file diff --git a/.idea/misc.xml b/.idea/misc.xml new file mode 100644 index 0000000..054629e --- /dev/null +++ b/.idea/misc.xml @@ -0,0 +1,10 @@ + + + + + + + + + + \ No newline at end of file diff --git a/.idea/uiDesigner.xml b/.idea/uiDesigner.xml new file mode 100644 index 0000000..2b63946 --- /dev/null +++ b/.idea/uiDesigner.xml @@ -0,0 +1,124 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + \ No newline at end of file diff --git a/.idea/vcs.xml b/.idea/vcs.xml new file mode 100644 index 0000000..35eb1dd --- /dev/null +++ b/.idea/vcs.xml @@ -0,0 +1,6 @@ + + + + + + \ No newline at end of file diff --git a/build.gradle.kts b/build.gradle.kts new file mode 100644 index 0000000..c2fe34f --- /dev/null +++ b/build.gradle.kts @@ -0,0 +1,26 @@ +plugins { + id("java") +} + +group = "com.cleverthis.interview" +version = "1.0-SNAPSHOT" + +repositories { + mavenCentral() +} + +dependencies { + implementation(project(":padlock-impl")) + + testImplementation(platform("org.junit:junit-bom:5.9.1")) + testImplementation("org.junit.jupiter:junit-jupiter") +} + +java { + sourceCompatibility = JavaVersion.VERSION_1_8 + targetCompatibility = JavaVersion.VERSION_1_8 +} + +tasks.test { + useJUnitPlatform() +} \ No newline at end of file diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar new file mode 100644 index 0000000..249e583 Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties new file mode 100644 index 0000000..a4071ed --- /dev/null +++ b/gradle/wrapper/gradle-wrapper.properties @@ -0,0 +1,6 @@ +#Tue Mar 12 14:12:45 CST 2024 +distributionBase=GRADLE_USER_HOME +distributionPath=wrapper/dists +distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-bin.zip +zipStoreBase=GRADLE_USER_HOME +zipStorePath=wrapper/dists diff --git a/gradlew b/gradlew new file mode 100755 index 0000000..1b6c787 --- /dev/null +++ b/gradlew @@ -0,0 +1,234 @@ +#!/bin/sh + +# +# Copyright © 2015-2021 the original authors. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +############################################################################## +# +# Gradle start up script for POSIX generated by Gradle. +# +# Important for running: +# +# (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is +# noncompliant, but you have some other compliant shell such as ksh or +# bash, then to run this script, type that shell name before the whole +# command line, like: +# +# ksh Gradle +# +# Busybox and similar reduced shells will NOT work, because this script +# requires all of these POSIX shell features: +# * functions; +# * expansions «$var», «${var}», «${var:-default}», «${var+SET}», +# «${var#prefix}», «${var%suffix}», and «$( cmd )»; +# * compound commands having a testable exit status, especially «case»; +# * various built-in commands including «command», «set», and «ulimit». +# +# Important for patching: +# +# (2) This script targets any POSIX shell, so it avoids extensions provided +# by Bash, Ksh, etc; in particular arrays are avoided. +# +# The "traditional" practice of packing multiple parameters into a +# space-separated string is a well documented source of bugs and security +# problems, so this is (mostly) avoided, by progressively accumulating +# options in "$@", and eventually passing that to Java. +# +# Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS, +# and GRADLE_OPTS) rely on word-splitting, this is performed explicitly; +# see the in-line comments for details. +# +# There are tweaks for specific operating systems such as AIX, CygWin, +# Darwin, MinGW, and NonStop. +# +# (3) This script is generated from the Groovy template +# https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt +# within the Gradle project. +# +# You can find Gradle at https://github.com/gradle/gradle/. +# +############################################################################## + +# Attempt to set APP_HOME + +# Resolve links: $0 may be a link +app_path=$0 + +# Need this for daisy-chained symlinks. +while + APP_HOME=${app_path%"${app_path##*/}"} # leaves a trailing /; empty if no leading path + [ -h "$app_path" ] +do + ls=$( ls -ld "$app_path" ) + link=${ls#*' -> '} + case $link in #( + /*) app_path=$link ;; #( + *) app_path=$APP_HOME$link ;; + esac +done + +APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit + +APP_NAME="Gradle" +APP_BASE_NAME=${0##*/} + +# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. +DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"' + +# Use the maximum available, or set MAX_FD != -1 to use that value. +MAX_FD=maximum + +warn () { + echo "$*" +} >&2 + +die () { + echo + echo "$*" + echo + exit 1 +} >&2 + +# OS specific support (must be 'true' or 'false'). +cygwin=false +msys=false +darwin=false +nonstop=false +case "$( uname )" in #( + CYGWIN* ) cygwin=true ;; #( + Darwin* ) darwin=true ;; #( + MSYS* | MINGW* ) msys=true ;; #( + NONSTOP* ) nonstop=true ;; +esac + +CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar + + +# Determine the Java command to use to start the JVM. +if [ -n "$JAVA_HOME" ] ; then + if [ -x "$JAVA_HOME/jre/sh/java" ] ; then + # IBM's JDK on AIX uses strange locations for the executables + JAVACMD=$JAVA_HOME/jre/sh/java + else + JAVACMD=$JAVA_HOME/bin/java + fi + if [ ! -x "$JAVACMD" ] ; then + die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME + +Please set the JAVA_HOME variable in your environment to match the +location of your Java installation." + fi +else + JAVACMD=java + which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. + +Please set the JAVA_HOME variable in your environment to match the +location of your Java installation." +fi + +# Increase the maximum file descriptors if we can. +if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then + case $MAX_FD in #( + max*) + MAX_FD=$( ulimit -H -n ) || + warn "Could not query maximum file descriptor limit" + esac + case $MAX_FD in #( + '' | soft) :;; #( + *) + ulimit -n "$MAX_FD" || + warn "Could not set maximum file descriptor limit to $MAX_FD" + esac +fi + +# Collect all arguments for the java command, stacking in reverse order: +# * args from the command line +# * the main class name +# * -classpath +# * -D...appname settings +# * --module-path (only if needed) +# * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables. + +# For Cygwin or MSYS, switch paths to Windows format before running java +if "$cygwin" || "$msys" ; then + APP_HOME=$( cygpath --path --mixed "$APP_HOME" ) + CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" ) + + JAVACMD=$( cygpath --unix "$JAVACMD" ) + + # Now convert the arguments - kludge to limit ourselves to /bin/sh + for arg do + if + case $arg in #( + -*) false ;; # don't mess with options #( + /?*) t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath + [ -e "$t" ] ;; #( + *) false ;; + esac + then + arg=$( cygpath --path --ignore --mixed "$arg" ) + fi + # Roll the args list around exactly as many times as the number of + # args, so each arg winds up back in the position where it started, but + # possibly modified. + # + # NB: a `for` loop captures its iteration list before it begins, so + # changing the positional parameters here affects neither the number of + # iterations, nor the values presented in `arg`. + shift # remove old arg + set -- "$@" "$arg" # push replacement arg + done +fi + +# Collect all arguments for the java command; +# * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of +# shell script including quotes and variable substitutions, so put them in +# double quotes to make sure that they get re-expanded; and +# * put everything else in single quotes, so that it's not re-expanded. + +set -- \ + "-Dorg.gradle.appname=$APP_BASE_NAME" \ + -classpath "$CLASSPATH" \ + org.gradle.wrapper.GradleWrapperMain \ + "$@" + +# Use "xargs" to parse quoted args. +# +# With -n1 it outputs one arg per line, with the quotes and backslashes removed. +# +# In Bash we could simply go: +# +# readarray ARGS < <( xargs -n1 <<<"$var" ) && +# set -- "${ARGS[@]}" "$@" +# +# but POSIX shell has neither arrays nor command substitution, so instead we +# post-process each arg (as a line of input to sed) to backslash-escape any +# character that might be a shell metacharacter, then use eval to reverse +# that process (while maintaining the separation between arguments), and wrap +# the whole thing up as a single "set" statement. +# +# This will of course break if any of these variables contains a newline or +# an unmatched quote. +# + +eval "set -- $( + printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" | + xargs -n1 | + sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' | + tr '\n' ' ' + )" '"$@"' + +exec "$JAVACMD" "$@" diff --git a/gradlew.bat b/gradlew.bat new file mode 100644 index 0000000..ac1b06f --- /dev/null +++ b/gradlew.bat @@ -0,0 +1,89 @@ +@rem +@rem Copyright 2015 the original author or authors. +@rem +@rem Licensed under the Apache License, Version 2.0 (the "License"); +@rem you may not use this file except in compliance with the License. +@rem You may obtain a copy of the License at +@rem +@rem https://www.apache.org/licenses/LICENSE-2.0 +@rem +@rem Unless required by applicable law or agreed to in writing, software +@rem distributed under the License is distributed on an "AS IS" BASIS, +@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +@rem See the License for the specific language governing permissions and +@rem limitations under the License. +@rem + +@if "%DEBUG%" == "" @echo off +@rem ########################################################################## +@rem +@rem Gradle startup script for Windows +@rem +@rem ########################################################################## + +@rem Set local scope for the variables with windows NT shell +if "%OS%"=="Windows_NT" setlocal + +set DIRNAME=%~dp0 +if "%DIRNAME%" == "" set DIRNAME=. +set APP_BASE_NAME=%~n0 +set APP_HOME=%DIRNAME% + +@rem Resolve any "." and ".." in APP_HOME to make it shorter. +for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi + +@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. +set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m" + +@rem Find java.exe +if defined JAVA_HOME goto findJavaFromJavaHome + +set JAVA_EXE=java.exe +%JAVA_EXE% -version >NUL 2>&1 +if "%ERRORLEVEL%" == "0" goto execute + +echo. +echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. +echo. +echo Please set the JAVA_HOME variable in your environment to match the +echo location of your Java installation. + +goto fail + +:findJavaFromJavaHome +set JAVA_HOME=%JAVA_HOME:"=% +set JAVA_EXE=%JAVA_HOME%/bin/java.exe + +if exist "%JAVA_EXE%" goto execute + +echo. +echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% +echo. +echo Please set the JAVA_HOME variable in your environment to match the +echo location of your Java installation. + +goto fail + +:execute +@rem Setup the command line + +set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar + + +@rem Execute Gradle +"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %* + +:end +@rem End local scope for the variables with windows NT shell +if "%ERRORLEVEL%"=="0" goto mainEnd + +:fail +rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of +rem the _cmd.exe /c_ return code! +if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1 +exit /b 1 + +:mainEnd +if "%OS%"=="Windows_NT" endlocal + +:omega diff --git a/padlock-impl/build.gradle.kts b/padlock-impl/build.gradle.kts new file mode 100644 index 0000000..0aa5bde --- /dev/null +++ b/padlock-impl/build.gradle.kts @@ -0,0 +1,19 @@ +plugins { + id("java") +} + +group = "com.cleverthis.interview" +version = "1.0-SNAPSHOT" + +repositories { + mavenCentral() +} + +dependencies { + testImplementation(platform("org.junit:junit-bom:5.9.1")) + testImplementation("org.junit.jupiter:junit-jupiter") +} + +tasks.test { + useJUnitPlatform() +} \ No newline at end of file diff --git a/padlock-impl/src/main/java/com/cleverthis/interview/padlock/Padlock.java b/padlock-impl/src/main/java/com/cleverthis/interview/padlock/Padlock.java new file mode 100644 index 0000000..fb8ebe6 --- /dev/null +++ b/padlock-impl/src/main/java/com/cleverthis/interview/padlock/Padlock.java @@ -0,0 +1,94 @@ +package com.cleverthis.interview.padlock; + +import java.security.InvalidParameterException; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; + +import static com.cleverthis.interview.padlock.Utils.ensureSleep; + +/** + * This is a logical representation of a physical padlock with a numpad. + *
+ * The padlock has the following features: + * + *
+ * After create, the input buffer is empty, you have to initialize. + */ +public class Padlock { + private final int numpadSize; + private final Integer[] inputBuffer; + private final Integer[] correctPasscode; + + /** + * Create a padlock instance. + * + * @param numpadSize The number of buttons on the numpad of this lock. + */ + public Padlock(int numpadSize) { + if (numpadSize < 1) throw new IllegalArgumentException("numpadSize must be a positive number"); + this.numpadSize = numpadSize; + this.inputBuffer = new Integer[numpadSize]; + List answer = new ArrayList<>(numpadSize); + for (int i = 0; i < numpadSize; i++) + answer.add(i); + Collections.shuffle(answer); + this.correctPasscode = answer.toArray(new Integer[0]); + } + + public int getNumpadSize() { + return numpadSize; + } + + /** + * Write a digit into padlock's input buffer. This is a very expensive operation. + * + * @param address The digits you want to write. Range: [0, numpadSize) + * @param keyIndex The key/button index you want to put here. Range: [0, numpadSize) + * @return The old value, null if not initialized. + */ + public synchronized Integer writeInputBuffer(int address, int keyIndex) { + ensureSleep(1000); + if (keyIndex < 0 || keyIndex >= numpadSize) + throw new IllegalArgumentException( + "keyIndex out of range. Keypad size: " + numpadSize + ", keyIndex: " + keyIndex); + Integer oldValue = inputBuffer[address]; + inputBuffer[address] = keyIndex; + return oldValue; + } + + /** + * Check if the input buffer contains a correct passcode. + * + * @return true if the passcode is correct; false if passcode is wrong. + * @throws IllegalStateException if the input buffer is not a valid passcode + */ + public synchronized boolean isPasscodeCorrect() { + // first check if the input is legal + boolean[] uniqueTestArr = new boolean[numpadSize]; + for (Integer i : inputBuffer) { + if (i == null) throw new IllegalStateException( + "Passcode invalid: contain uninitialized value. " + Arrays.toString(inputBuffer)); + if (uniqueTestArr[i]) throw new IllegalStateException( + "Passcode invalid: contain duplicated value. " + Arrays.toString(inputBuffer)); + uniqueTestArr[i] = true; + } + // if no exception, means: + // every digit is unique, and every digit is initialized + // aka this is a valid code + // now compare with our answer + return Arrays.equals(correctPasscode, inputBuffer); + } +} \ No newline at end of file diff --git a/padlock-impl/src/main/java/com/cleverthis/interview/padlock/Utils.java b/padlock-impl/src/main/java/com/cleverthis/interview/padlock/Utils.java new file mode 100644 index 0000000..118f6a3 --- /dev/null +++ b/padlock-impl/src/main/java/com/cleverthis/interview/padlock/Utils.java @@ -0,0 +1,22 @@ +package com.cleverthis.interview.padlock; + +class Utils { + /** + * Ensure we will wait a given amount of time even if there are interruptions. + * + * @param millis The time you want to sleep, measure in millisecond. + */ + public static void ensureSleep(long millis) { + long endTime = System.currentTimeMillis() + millis; + while (endTime > System.currentTimeMillis()) { + try { + //noinspection BusyWait + Thread.sleep(endTime - System.currentTimeMillis()); + } catch (InterruptedException e) { + // do nothing when interrupted, will re-sleep in next loop + } catch (IllegalArgumentException e) { + break; + } + } + } +} diff --git a/settings.gradle.kts b/settings.gradle.kts new file mode 100644 index 0000000..3c0924d --- /dev/null +++ b/settings.gradle.kts @@ -0,0 +1,2 @@ +rootProject.name = "padlock" +include("padlock-impl")