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Advent of Code 2023: Day 3 Solution

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Table of Contents

Part 1 Solution

Read the Puzzle Input File

We will save our puzzle input in "day3_input.txt" and then read from that file.

file = open("day3_input.txt", "r")
input = file.read()

We will then break up the input by line:

input_list = input.split('\n')

The Code

# part 1
cur_num = []
sum = 0
for y in range(0, len(input_list)):
    for x in range(0, len(input_list[0])):
        if input_list[y][x].isnumeric():
            cur_num.append(input_list[y][x])
        
        if not input_list[y][x].isnumeric() or x == (len(input_list[0])-1):
            length = len(cur_num)
            if length > 0:
                x_start = max(0, x-length-1)
                x_end = min(len(input_list[0])-1, x)
                y_start = max(0, y-1)
                y_end = min(len(input_list)-1, y+1)

                flag = False
                for xx in range(x_start, x_end+1):
                    for yy in range(y_start, y_end+1):
                        if (input_list[yy][xx] != '.' and 
                            not input_list[yy][xx].isnumeric()):
                            sum += int("".join(cur_num))
                            cur_num = []
                            flag = True
                            break
                    if flag:
                        break
                cur_num = []
print(sum) 

Part 1 Visualization


Part 2 Solution

Read the Puzzle Input File

We have the same puzzle input as part 1, so again we will save our puzzle input in "day3_input.txt" and then read from that file.

file = open("day3_input.txt", "r")
input = file.read()

Again, we will break up the input by line:

input_list = input.split('\n')

The Code

# part 2
sum = 0
for y in range(0, len(input_list)):
    for x in range(0, len(input_list[0])):
        nums = []
        if input_list[y][x] == '*':
            length = 1
            x_start = max(0, x-length)
            x_end = min(len(input_list[0])-1, x+1)
            y_start = max(0, y-1)
            y_end = min(len(input_list)-1, y+1)

            considered = []
            for xx in range(x_start, x_end+1):
                for yy in range(y_start, y_end+1):
                    if input_list[yy][xx].isnumeric() and [xx, yy] not in considered:
                        x2 = xx
                        cur_num = []
                        while True:
                            x2 -= 1
                            if x2>=0:
                                if not input_list[yy][x2].isnumeric():
                                    break
                            else:
                                break
                        x2+=1
                        while True:
                            if x2 < len(input_list[0]):
                                if input_list[yy][x2].isnumeric():
                                    considered.append([x2, yy])
                                    cur_num.append(input_list[yy][x2])
                                    x2+=1
                                else:
                                    break
                            else:
                                break
                        nums.append(int("".join(cur_num)))
            if len(nums) == 2:
                sum += nums[0]*nums[1]
print(sum)  

Full code

Get the full code here.

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