Advent of Code 2021 Python Solution: Day 11
Tags: python, adventofcode, algorithms
Published: 2021-12-11 14:06:15

Today's challenge was harder than previous day's.

```python
adj = [(i,j) for i in range(-1, 2) for j in range(-1,2) if i!=0 or j!=0]
window = {(i,j):darr[i][j] for i in range(10) for j in range(10)}

flashes = 0
i=0
previous = set()

while len(previous)<len(window):
    previous = set()
    window = {k:v+1 for k, v in window.items()}
    while True:
        if sum(v>9 for k,v in window.items() if k not in previous)==0:
            break
            
        for k,v in window.items():
            if k not in previous and v>9:
                previous.add(k)
                for ad in [(k[0]+i,k[1]+j) for i,j in adj if (k[0]+i,k[1]+j) in window]:
                    window[ad]+=1
    
    flashes+=len(previous)
    window.update({k:0 for k in previous})
    i+=1
    if i==100:
        print(f"Part 1: {flashes}")
    
print(f"Part 2: {i}")
```

## Why not read more?
* [Gesture Based Visually Writing System Using OpenCV and Python](https://q-viper.github.io/2020/08/01/gesture-based-visually-writing-system-using-opencv-and-python/)
* [Gesture Based Visually Writing System: Adding Visual User Interface](https://q-viper.github.io/2020/08/11/gesture-based-visually-writing-system-make-a-visual-user-interface/)
* [Gesture Based Visually Writing System: Adding Virtual Animationn, New Mode and New VUI](https://q-viper.github.io/2020/08/14/gesture-based-visually-writing-system-adding-virtual-animation-new-mode-and-new-vui/)
* [Gesture Based Visually Writing System: Add Slider, More Colors and Optimized OOP code](https://q-viper.github.io/2020/08/21/gesture-based-visually-writing-system-add-slider-more-colors-and-optimized-code/)
* [Gesture Based Visually Writing System: A Web App](https://q-viper.github.io/2020/08/29/gesture-based-visually-writing-system-web-app/)
* [Contour Based Game: Break The Bricks](https://q-viper.github.io/2020/08/16/contour-based-game-break-the-bricks/)
* [Linear Regression from Scratch](https://q-viper.github.io/2020/08/07/writing-a-linear-regression-class-from-scratch-using-python/)
* [Writing Popular ML Optimizers from Scratch](https://q-viper.github.io/2020/06/05/writing-popular-machine-learning-optimizers-from-scratch-on-python/)
* [Feed Forward Neural Network from Scratch](https://q-viper.github.io/2020/05/30/writing-a-deep-neural-network-from-scratch-on-python/)
* [Convolutional Neural Networks from Scratch](https://q-viper.github.io/2020/06/05/convolutional-neural-networks-from-scratch-on-python/)
* [Writing a Simple Image Processing Class from Scratch](https://q-viper.github.io/2020/05/30/image-processing-class-from-scratch-on-python/)
* [Deploying a RASA Chatbot on Android using Unity3d](https://q-viper.github.io/2020/08/04/deploying-a-simple-rasa-chatbot-on-unity3d-project-to-make-a-chatbot-for-android-devices/)
* [Naive Bayes for text classifications: Scratch to Framework](https://q-viper.github.io/2020/03/04/text-classification-using-naive-bayes-scratch-to-the-framework/)
* [Simple OCR for Devanagari Handwritten Text](https://q-viper.github.io/2020/02/25/building-ocr-for-devanagari-handwritten-character/)