20240904

• Ordered running vest/shorts/shirts on Amazon
• Checked the code of PyMuPDF
  • How they manage flags is interesting. They use an integer, and all different flags are assigned 1, 2, 4, 8, …, so the flags can be combined easily and managed effectively.
  • If I were to design that, I might have created some kind of object. It was good to know.

I hope I can wake up a bit early tomorrow to go for a jogging.

2008B. Square or Not

My approach:

1. Check if it's possible to make a square with the given number of blocks
2. If it's possible, create the expected string and compare it with the input

It just worked, but I didn't use the constraint

The second line of each test case contains the string s of length n. The string is always the result of writing out the strings of a beautiful matrix.

def root(n: int) -> int:
    li: int = 0
    ri: int = n
    while li < ri - 1:
        mi: int = (li + ri) // 2
        sq: int = mi * mi
        if sq == n:
            return mi
        elif sq > n:
            ri = mi
        else:
            li = mi

    return li if li * li == n else -1


for _ in range(int(input())):
    n: int = int(input())
    s: str = input()

    r = c = root(n)
    if r == -1:
        print("No")
        continue

    sq: str = ""
    sq += "1" * r
    for i in range(r - 2):
        sq += "1" + "0" * (r - 2) + "1"
    sq += "1" * r

    if s == sq:
        print("Yes")
    else:
        print("No")

Codeforces Round 970 (Div. 3) Editorial

Assume that string was created from the beautiful binary matrix with size r * c.

If r <= 2 or c <= 2, then the whole matrix consists of ‘1’. This means that the string will have only one character and this is the onlly case such happening. So, if the whole string is constructed out of ‘1’, we print “Yes” only if the size of the string is 4, since only r = c = 2 is a good matrix for us.

I can understand the solution so far.

Otherwise, we have at least one ‘0’ in the string. Let's look at what is the index of the first ‘0’.

If it has index r + 1, since the whole first line and first character of the first line equal to ‘1’, so now, we have a fixed value of r (index of the first ‘0’ minus 1) and the answer is “Yes” only if r is the square root of n.

I see. Because it's guaranteed that the input string is already a beautiful one, calculating r is enough to solve the problem. Genius.

My solution of 2008A and 2008B are different from the optimal, but I managed to pass the tests. It's interesting.

I remember that someone said the flexibility of the solutions is an exciting point of competitive programming.

Rice 700 Salad 400 Protein shake 200 Bagels 500 Protein shake 200 Nori 100 Kombucha 100

Total 2200 kcal

pull-ups, push-ups

MUST:

• Make notes on how flags of PyMuPDF is implemented.

TODO:

• Retry 2008A with a mathematical approach
• Retry 2008B with a mathematical approach
• Review 2008C
• Review 2008D
• Ask the house agent about utility bills
• Self-guided tour, 20240914 3:00 pm

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