Advent of Code 2020: Python Solution Day 7
Tags: adventofcode, algorithms, python, 100daysofcode
Published: 2020-12-07 09:15:44

This challenge is the most hardest challenge I am ever doing and this sounds like DFS(Depth First Search) after scratching head for hours, I found one solution for part 1. Again, I saved my input as `day7.txt` along with the example input `day7_test.txt` on the same directory as my notebook is. I also have updated my [GitHub repository]().

## Solution to Challenge 1
```python
with open("day7.txt", "r") as fp:
    lines = fp.readlines()
    lines=[line.rstrip() for line in lines]

# to make a dictionary of bags
bag_types = []
all_bags = {}
for line in lines:
    mbag = " ".join(line.split(" ")[:2])
    contains = line[line.index("contain ")+8:-1]
    each_contain = contains.split(",")
    each_contain = [cnt.lstrip() for cnt in each_contain]
    each_contain = [" ".join(cont.split(" ")[:-1]) for cont in each_contain]
    #print(each_contain)
    each_contain = {" ".join(cont.split(" ")[1:]):cont.split(" ")[0] for cont in each_contain}
    #print(each_contain)
    if mbag not in bag_types:
        bag_types.append(mbag)
    if all_bags.get(mbag):
        each_contain.update(all_bags[mbag]) 
    all_bags[mbag] = each_contain

def check_bag(bags, my_bag, current_bag):
    if current_bag==my_bag:
        return 1
    if bags.get(current_bag) is None:
        return 0
    else:
        counts = []
        for k, v in bags[current_bag].items():
            counts.append(check_bag(bags, my_bag, k))
        return max(counts)

found_bags = 0
my_bag = "shiny gold"
for k, v in all_bags.items():
    if k != my_bag:
        found_bags+=check_bag(all_bags, my_bag, k)
print(f"{found_bags} bags can contain {my_bag} bag.")
```

## Solution to Challenge 2
This was even more tough for me and I regularly has to write algorithm.

```python
"""
    shiny gold bags contain 2 dark red bags.
    dark red bags contain 2 dark orange bags.
    dark orange bags contain 2 dark yellow bags.
    dark yellow bags contain 2 dark green bags.
    dark green bags contain 2 dark blue bags.
    dark blue bags contain 2 dark violet bags.
    dark violet bags contain no other bags.

    i.e. 1 shiny = 2 red + 2 red * 2 orange + 2 red * 2 orange * 2 yellow + 
                  2 red * 2 orange * 2 yellow * 2 green + 2 red * 2 orange * 2 yellow * 2 green * 2 blue+
                  2 red * 2 orange * 2 yellow * 2 green * 2 blue * 2 dark violet + 
                  2 red * 2 orange * 2 yellow * 2 green * 2 blue * 2 dark violet * 0 dark violet
                = 2 + 2**2 + 2**3 + 2 ** 4 + 2 ** 5 + 2 ** 6
                = 126
"""
test_bags = {"shiny gold": {"dark red": 2},
            "dark red": {"dark orange": 2},
            "dark orange": {"dark yellow": 2},
            "dark yellow": {"dark green": 2},
            "dark green": {"dark blue": 2},
            "dark blue": {"dark violet": 2},
            "dark violet": 0}

my_bag = "shiny gold"
bags_contains = {}
test_bags=all_bags
for k, v in test_bags.items():
    bags_contains[k] = []
    try:
        for kk, vv in v.items():
            
            bags_contains[k]+=[kk]*int(vv)
    except:
        pass
c=0

def count_bags(current_bag):
    if current_bag==" " or bags_contains.get(current_bag) is None:
        return 0

    #print("key:", current_bag)
    cnt = len(bags_contains[current_bag])
    cnts = []
    for k in bags_contains[current_bag]:
        cnts.append(count_bags(k))    
    return sum(cnts)+cnt

print(f"{my_bag} bag can hold {count_bags('shiny gold')} bags")
```
PHEW!!!
I write blogs about Computer Vision projects on my GitHub page [q-viper.github.io](https://q-viper.github.io) and if you got some time please share yours too.