#include <Keypad.h>

const int analogPin = A0;
const int ledCount = 10;

int ledPins[] = {
  2, 3, 4, 5, 6, 7, 8, 9, 10, 11
};

const uint8_t ROWS = 3;
const uint8_t COLS = 3;
char keys[ROWS][COLS] = {
  { '1', '2', '3' },
  { '4', '5', '6' },
  { '7', '8', '9' }
};

uint8_t colPins[COLS] = { 5, 4, 3, 2 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {

  Serial.begin(9600);

  for (int thisLed = 0; thisLed < ledCount; thisLed++) {
    pinMode(ledPins[thisLed], OUTPUT);
  }

}

void loop() {

  char key = keypad.getKey(); // Keypad

  int sensorReading = analogRead(analogPin); // Potentiometer
  int ledLevel = map(sensorReading, 0, 1023, 0, ledCount); // Potentiometer

  for (int thisLed = 0; thisLed < ledCount; thisLed++) { // Potentiometer
    if (thisLed < ledLevel) {
      digitalWrite(ledPins[thisLed], HIGH);
    }
    else {
      digitalWrite(ledPins[thisLed], LOW);
    }
  }

  if (key != NO_KEY) { // Keypad
    Serial.println(key);
  }
}