Allow enabling sqrt optimizations while computing

qml/Main.qml

@@ -22,12 +22,14 @@ ApplicationWindow {
             Layout.fillWidth: true
 
             ColumnLayout {
+                anchors.fill: parent
                 spacing: 10
 
                 TextField {
                     id: numberInput
                     placeholderText: "Enter a number"
                     // NOTE: We can't use the IntValidator here, since it doesn't support 64-bit values (long long)
+                    // Entering invalid numbers might cause unexpected behavior (will be fed to parseInt).
                     Layout.fillWidth: true
                     font.pixelSize: 16
                     onTextChanged: factorizationController.reset()
@@ -49,10 +51,16 @@ ApplicationWindow {
                     }
 
                     Button {
-                        text: "Pause"
+                        text: factorizationController.isPaused ? "Reset" : factorizationController.isRunning ? "Pause" : "Reset"
                         Layout.fillWidth: true
-                        enabled: factorizationController.isRunning
-                        onClicked: factorizationController.stop()
+                        enabled: factorizationController.isRunning || factorizationController.isPaused
+                        onClicked: {
+                            if (factorizationController.isPaused) {
+                                factorizationController.reset();
+                            } else {
+                                factorizationController.stop();
+                            }
+                        }
                     }
                 }
             }
@@ -61,7 +69,9 @@ ApplicationWindow {
         GroupBox {
             title: "Settings"
             Layout.fillWidth: true
+
             ColumnLayout {
+                anchors.fill: parent
                 spacing: 10
 
                 RowLayout {
@@ -89,37 +99,64 @@ ApplicationWindow {
                     }
                 }
 
-                CheckBox {
-                    text: "Stop at sqrt(n)"
-                    checked: true
-                    onCheckedChanged: factorizationController.useSqrtOptimization = checked
+                RowLayout {
+                    Layout.fillWidth: true
+
+                    CheckBox {
+                        text: "Stop at sqrt(n)"
+                        checked: factorizationController.useSqrtOptimization
+                        onCheckedChanged: factorizationController.useSqrtOptimization = checked
+                    }
+
+                    CheckBox {
+                        text: "Pause when factor found"
+                        checked: factorizationController.pauseOnFound
+                        onCheckedChanged: factorizationController.pauseOnFound = checked
+                    }
                 }
             }
         }
 
-        ProgressBar {
-            Layout.fillWidth: true
-            from: 0
-            to: 100
-            value: factorizationController.progress
-        }
-
         GroupBox {
             title: "Current Status"
             Layout.fillWidth: true
-            ColumnLayout {
-                spacing: 5
 
-                Text {
-                    text: "Current Factor: " + factorizationController.currentFactor
-                    font.pixelSize: 14
-                    Layout.alignment: Qt.AlignHCenter
-                }
+            ColumnLayout {
+                anchors.fill: parent
+                spacing: 5
 
                 Text {
                     text: "Current Number (being factorized): " + factorizationController.curFactNumber
                     font.pixelSize: 14
-                    Layout.alignment: Qt.AlignHCenter
+                }
+
+                Text {
+                    text: "Current Factor: " + factorizationController.currentFactor
+                    font.pixelSize: 14
+                }
+
+                Text {
+                    text: "Stop Factor: " + factorizationController.stopFactor
+                    font.pixelSize: 14
+                }
+
+                Item {
+                    Layout.fillWidth: true
+                    Layout.preferredHeight: 25
+
+                    ProgressBar {
+                        anchors.fill: parent
+                        to: 100
+                        value: factorizationController.progress
+                    }
+
+                    Text {
+                        text: factorizationController.progress.toFixed(1) + "%"
+                        anchors.centerIn: parent
+                        font.pixelSize: 16
+                        color: "black"
+                        font.bold: true
+                    }
                 }
             }
         }
@@ -137,7 +174,7 @@ ApplicationWindow {
         }
 
         Text {
-            text: factorizationController.useSqrtOptimization ? "Note: Only factors up to sqrt(n) are searched." : "Note: Searching all factors (slower)."
+            text: factorizationController.useSqrtOptimization ? "Note: Only factors up to sqrt(n) are searched." : "Warning: Searching all factors (inefficient)."
             font.pixelSize: 12
             Layout.alignment: Qt.AlignHCenter
         }

src/FactorizationController.cpp

@@ -3,30 +3,37 @@
 #include <cmath>
 
 FactorizationController::FactorizationController(QObject* parent) :
-    QObject{parent}, m_isRunning(false), m_useSqrtOptimization(true), m_iterationsPerCycle(1), m_currentFactNumber(0), m_currentFactor(2) {
+    QObject{parent}, m_isRunning(false), m_useSqrtOptimization(true), m_pauseOnFound(false), m_iterationsPerCycle(1), m_currentFactNumber(0), m_originalNumber(0),
+    m_currentFactor(0), m_stopFactor(0) {
     assert(connect(&m_timer, &QTimer::timeout, this, &FactorizationController::onTimerTick));
 }
 
-long long FactorizationController::number() const {
+unsigned long long FactorizationController::number() const {
     return m_originalNumber;
 }
 
-long long FactorizationController::curFactNumber() const {
+unsigned long long FactorizationController::curFactNumber() const {
     return m_currentFactNumber;
 }
 
-int FactorizationController::progress() const {
-    // If current factor is at or below 2 already, we must be done,
-    // stopFactor can never be less than 2, that makes no sense.
-    if (m_currentFactNumber == 1 || m_currentFactor <= 2 || m_currentFactor > m_stopFactor)
+double FactorizationController::progress() const {
+    // If the original number is set to 0, the computation wasn't yet initialized / was reset.
+    // If the current factor is at 2, the computation has just started, return early to avoid
+    // zero division issues.
+    if (m_originalNumber == 0 || m_currentFactor <= 2)
+        return 0;
+
+    // If the current number being factorized is 1, we must be done, all factors were found
+    // Alternatively, we're also done when the current factor passes the stop factor.
+    if (m_currentFactNumber == 1 || m_currentFactor > m_stopFactor)
         return 100;
 
     // Determine the progress based on the current factor, in comparison to stop factor.
     // since factor being <= 2 means 100%, we sub 2 here.
     double progress = static_cast<double>(m_currentFactor - 2) / static_cast<double>(m_stopFactor - 2);
 
-    // Return the value as int percentage
-    return static_cast<int>(std::clamp(progress * 100, 0.0, 100.0));
+    // Return the value as percentage
+    return std::clamp(progress * 100, 0.0, 100.0);
 }
 
 bool FactorizationController::isFinished() const {
@@ -51,7 +58,29 @@ void FactorizationController::setUseSqrtOptimization(bool value) {
 
     m_useSqrtOptimization = value;
     emit useSqrtOptimizationChanged();
-    reset();
+
+    // We're in a reset state
+    if (m_originalNumber == 0)
+        return;
+
+    if (m_useSqrtOptimization)
+        m_stopFactor = static_cast<unsigned long long>(std::sqrt(m_currentFactNumber));
+    else
+        m_stopFactor = m_currentFactNumber - 1;
+    emit stopFactorChanged();
+    emit progressChanged();
+}
+
+bool FactorizationController::pauseOnFound() const {
+    return m_pauseOnFound;
+}
+
+void FactorizationController::setPauseOnFound(bool value) {
+    if (value == m_pauseOnFound)
+        return;
+
+    m_pauseOnFound = value;
+    emit pauseOnFoundChanged();
 }
 
 int FactorizationController::iterationsPerCycle() const {
@@ -66,21 +95,31 @@ void FactorizationController::setIterationsPerCycle(int number) {
     emit iterationsPerCycleChanged();
 }
 
-long long FactorizationController::currentFactor() const {
+unsigned long long FactorizationController::currentFactor() const {
     return m_currentFactor;
 }
 
-QList<long long> FactorizationController::factors() const {
+unsigned long long FactorizationController::stopFactor() const {
+    return m_stopFactor;
+}
+
+QList<unsigned long long> FactorizationController::factors() const {
     return m_factors;
 }
 
-void FactorizationController::start(long long number) {
+void FactorizationController::start(unsigned long long number) {
     m_originalNumber = number;
     m_currentFactNumber = number;
     m_currentFactor = 2;
     m_isRunning = true;
     m_isFinished = false;
     m_factors.clear();
+    if (m_useSqrtOptimization) {
+        // we could also just compute this every time, but sqrt is pretty expensive
+        m_stopFactor = static_cast<unsigned long long>(std::sqrt(m_currentFactNumber));
+    } else {
+        m_stopFactor = m_currentFactNumber - 1;
+    }
     emit isRunningChanged();
     emit isFinishedChanged();
     emit numberChanged();
@@ -88,13 +127,7 @@ void FactorizationController::start(long long number) {
     emit progressChanged();
     emit factorsChanged();
     emit curFactNumberChanged();
-
-    if (m_useSqrtOptimization) {
-        // we could also just compute this every time, but sqrt is pretty expensive
-        m_stopFactor = static_cast<long long>(std::sqrt(m_currentFactNumber));
-    } else {
-        m_stopFactor = m_currentFactNumber - 1;
-    }
+    emit stopFactorChanged();
 
     m_timer.start(0);
 }
@@ -134,13 +167,17 @@ void FactorizationController::reset() {
         return;
 
     m_isPaused = false;
-    m_currentFactNumber = m_originalNumber;
-    m_currentFactor = 2;
+    m_originalNumber = 0;
+    m_currentFactNumber = 0;
+    m_currentFactor = 0;
+    m_stopFactor = 0;
     m_factors.clear();
     emit isPausedChanged();
     emit currentFactorChanged();
-    emit progressChanged();
+    emit curFactNumberChanged();
     emit factorsChanged();
+    emit stopFactorChanged();
+    emit progressChanged();
 }
 
 void FactorizationController::onTimerTick() {
@@ -189,12 +226,16 @@ void FactorizationController::factorize() {
         // the new number being factorized, rather than keeping it at the original number.
         // (This might make the progress bar jump radically)
         if (m_useSqrtOptimization) {
-            m_stopFactor = static_cast<long long>(std::sqrt(m_currentFactNumber));
+            m_stopFactor = static_cast<unsigned long long>(std::sqrt(m_currentFactNumber));
         } else {
             m_stopFactor = m_currentFactNumber - 1;
         }
+        emit stopFactorChanged();
         emit progressChanged();
 
+        if (m_pauseOnFound)
+            stop();
+
         // Don't increase current factor, keep dividing by it until no longer divisible
     } else {
         m_currentFactor++;

src/FactorizationController.h

@@ -26,11 +26,13 @@ class FactorizationController : public QObject {
     Q_PROPERTY(bool isPaused READ isPaused NOTIFY isPausedChanged)
     Q_PROPERTY(int iterationsPerCycle READ iterationsPerCycle WRITE setIterationsPerCycle NOTIFY iterationsPerCycleChanged)
     Q_PROPERTY(bool useSqrtOptimization READ useSqrtOptimization WRITE setUseSqrtOptimization NOTIFY useSqrtOptimizationChanged)
-    Q_PROPERTY(long long number READ number NOTIFY numberChanged)
-    Q_PROPERTY(long long curFactNumber READ curFactNumber NOTIFY curFactNumberChanged)
-    Q_PROPERTY(long long currentFactor READ currentFactor NOTIFY currentFactorChanged)
-    Q_PROPERTY(int progress READ progress NOTIFY progressChanged)
-    Q_PROPERTY(QList<long long> factors READ factors NOTIFY factorsChanged)
+    Q_PROPERTY(bool pauseOnFound READ pauseOnFound WRITE setPauseOnFound NOTIFY pauseOnFoundChanged)
+    Q_PROPERTY(unsigned long long number READ number NOTIFY numberChanged)
+    Q_PROPERTY(unsigned long long curFactNumber READ curFactNumber NOTIFY curFactNumberChanged)
+    Q_PROPERTY(unsigned long long currentFactor READ currentFactor NOTIFY currentFactorChanged)
+    Q_PROPERTY(unsigned long long stopFactor READ stopFactor NOTIFY stopFactorChanged)
+    Q_PROPERTY(double progress READ progress NOTIFY progressChanged)
+    Q_PROPERTY(QList<unsigned long long> factors READ factors NOTIFY factorsChanged)
 
   public:
     explicit FactorizationController(QObject* parent = nullptr);
@@ -41,7 +43,7 @@ class FactorizationController : public QObject {
      * @brief Gets the current progress of factorization.
      * @return The progress percentage (0-100).
      */
-    int progress() const;
+    double progress() const;
 
     /**
      * @brief Checks if the factorization process is running.
@@ -87,11 +89,17 @@ class FactorizationController : public QObject {
      */
     bool useSqrtOptimization() const;
 
+    /**
+     * @brief Checks whether the computation should be paused once a new factor is found.
+     * @return True if the computation will get paused on new factor being found, otherwise False.
+     */
+    bool pauseOnFound() const;
+
     /**
      * @brief Gets the original number being factorized.
      * @return The number being factorized.
      */
-    long long number() const;
+    unsigned long long number() const;
 
     /**
      * @brief The current number being factorized.
@@ -100,7 +108,7 @@ class FactorizationController : public QObject {
      * As the factorization process is going on, the number being factorized might change
      * from the original number, as we're dividing it by the found factors.
      */
-    long long curFactNumber() const;
+    unsigned long long curFactNumber() const;
 
     /**
      * @brief Gets the current factor being tested.
@@ -110,7 +118,17 @@ class FactorizationController : public QObject {
      * is a factor, going one by one. This returns the current factor (to be checked in the
      * next iteration).
      */
-    long long currentFactor() const;
+    unsigned long long currentFactor() const;
+
+    /**
+     * @brief Get the number at which the factorization process will stop
+     * @return The current stop factor.
+     *
+     * The stop factor determines at which factor will the factorization process be stopped.
+     * If sqrt optimizations are enabled, this will generally be the square root of the number
+     * currently being factorized. If not, it will be the number being factorized - 1.
+     */
+    unsigned long long stopFactor() const;
 
     /**
      * @brief Gets the list of discovered factors (may not be complete).
@@ -120,7 +138,7 @@ class FactorizationController : public QObject {
      * be complete (if the computation is still running). If you need to know whether you
      * can trust this result, check isFinished first.
      */
-    QList<long long> factors() const;
+    QList<unsigned long long> factors() const;
 
     // endregion
     // region: Setters
@@ -149,11 +167,20 @@ class FactorizationController : public QObject {
      * Generally, there's no reason to disable this optimization, however, if you wish to
      * perform a slower search, it is a way to achieve that.
      *
-     * Note that changing this value while the computation is in progress will reset the
-     * computation.
+     * This value can be changed even as a computation is ongoing; if you do so, the stop factor
+     * will change immediately, which will very likely cause the progress bar to rapidly change.
+     * It is possible that after enabling, the computation will immediately finish, as the stop
+     * factor will be less than the sqrt(x).
      */
     void setUseSqrtOptimization(bool value);
 
+    /**
+     * @brief Enable or disable auto-pausing on new factor being found.
+     *
+     * This value can be changed even as a computation is ongoing.
+     */
+    void setPauseOnFound(bool value);
+
     // endregion
     // region: Functions
 
@@ -164,7 +191,7 @@ class FactorizationController : public QObject {
      * This will start a 0-tick timer, which triggers a partial computation on each run,
      * to let the event loop cycle in between. This implementation does NOT rely on threads.
      */
-    Q_INVOKABLE void start(long long number);
+    Q_INVOKABLE void start(unsigned long long number);
 
     /**
      * @brief Stops the ongoing factorization process.
@@ -197,12 +224,14 @@ class FactorizationController : public QObject {
     void isFinishedChanged();
     void isPausedChanged();
     void useSqrtOptimizationChanged();
+    void pauseOnFoundChanged();
     void iterationsPerCycleChanged();
     void numberChanged();
     void currentFactorChanged();
     void factorsChanged();
     void progressChanged();
     void curFactNumberChanged();
+    void stopFactorChanged();
 
   private slots:
     void onTimerTick();
@@ -212,12 +241,13 @@ class FactorizationController : public QObject {
     bool m_isFinished; ///< Indicates whether the factorization process is done.
     bool m_isPaused; ///< Indicates whether the factorization process is paused (can be resumed).
     bool m_useSqrtOptimization; ///< Indicates whether to use the sqrt optimization
+    bool m_pauseOnFound; ///< Indicates whether the computation should be paused when a new factor is found.
     int m_iterationsPerCycle; ///< The number of iterations to perform per cycle.
-    long long m_currentFactNumber; ///< The number currently being factorized.
-    long long m_originalNumber; ///< The original input number.
-    long long m_currentFactor; ///< The current divisor being checked.
-    long long m_stopFactor; ///< The stopping limit (square root of original number, saved for efficiency).
-    QList<long long> m_factors; ///< List of discovered prime factors.
+    unsigned long long m_currentFactNumber; ///< The number currently being factorized.
+    unsigned long long m_originalNumber; ///< The original input number.
+    unsigned long long m_currentFactor; ///< The current divisor being checked.
+    unsigned long long m_stopFactor; ///< The stopping limit (square root of original number, saved for efficiency).
+    QList<unsigned long long> m_factors; ///< List of discovered prime factors.
     QTimer m_timer; ///< Timer for stepwise execution.
 
     /**