Advent of Code 2021 Python Solution: Day 9

First part was not much harder to crack but it still took plenty of time. But second part was tricky.

Part 1

import numpy as np
data,data1 = get_data(day=9)

dl = len(data1[0])
dt = np.array([int(d) for dt in data1 for d in dt])
dt = dt.reshape(-1, dl)

nums = []
pos = []
dc = len(dt[0])
dr = len(dt)
for r in range(len(dt)):
    for c in range(len(dt[0])):
        if r==0:
            if c==0:
                if dt[r,c]<dt[r+1, c] and dt[r,c]<dt[r, c+1]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
            elif c==dc-1:
                if dt[r,c]<dt[r+1, c] and dt[r,c]<dt[r, c-1]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
            else:
                if dt[r,c]<dt[r+1, c] and dt[r,c]<dt[r, c+1] and dt[r,c]<dt[r, c-1]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
        elif r==dr-1:
            if c==0:
                if dt[r,c]<dt[r-1, c] and dt[r,c]<dt[r, c+1]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
            elif c==dc-1:
                if dt[r,c]<dt[r-1, c] and dt[r,c]<dt[r, c-1]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
            else:
                if dt[r,c]<dt[r-1, c] and dt[r,c]<dt[r, c+1] and dt[r,c]<dt[r, c-1]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
        else:
            if c==0:
                if dt[r,c]<dt[r-1, c] and dt[r,c]<dt[r, c+1] and dt[r,c]<dt[r+1, c]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
            elif c==dc-1:
                if dt[r,c]<dt[r-1, c] and dt[r,c]<dt[r, c-1] and dt[r,c]<dt[r+1, c]:
                    nums.append(dt[r,c])
                    pos.append((r,c))
            else:
                if dt[r,c]<dt[r-1, c] and dt[r,c]<dt[r, c+1] and dt[r,c]<dt[r, c-1] and dt[r,c]<dt[r+1, c]:
                    nums.append(dt[r,c])
                    pos.append((r,c))


nums

Part 2

I thought I had to use some sort of Searching algorithm like DFS or BFS but I found a solution on StackOverflow using NumPy.

from scipy import ndimage

label, num_label = ndimage.label(dt < 9)
size = np.bincount(label.ravel())

top3 = sorted(size[1:], reverse=True)[:3]
print(np.prod(top3))

Why not read more?

• Gesture Based Visually Writing System Using OpenCV and Python
• Gesture Based Visually Writing System: Adding Visual User Interface
• Gesture Based Visually Writing System: Adding Virtual Animationn, New Mode and New VUI
• Gesture Based Visually Writing System: Add Slider, More Colors and Optimized OOP code
• Gesture Based Visually Writing System: A Web App
• Contour Based Game: Break The Bricks
• Linear Regression from Scratch
• Writing Popular ML Optimizers from Scratch
• Feed Forward Neural Network from Scratch
• Convolutional Neural Networks from Scratch
• Writing a Simple Image Processing Class from Scratch
• Deploying a RASA Chatbot on Android using Unity3d
• Naive Bayes for text classifications: Scratch to Framework
• Simple OCR for Devanagari Handwritten Text