Meta Hacker Cup 2024

Oct 5 2024 · 7 min · C++, MacOS

I got to know about it when I started cp.

Participated in the practice round 2024 for the first time.

• Faced many issues.
• Spent 5+ hours on just 2 problems because was not able to handle files and was new to system.
• After reading blogs and looking up the internet, here is a minimalist bash script to run your solution on MacOS (15.0+).

Usage :

• Create the following files :

Directory/
├── Sol.cpp
├── input.txt
├── output.txt
└── run.sh

• Navigate to the directory. paste the following code as given exactly (atleast the 4th line) in run.sh

#!/bin/bash

echo "Compiling Sol.cpp ..."
g++ -Wall -Wl,-stack_size,20000000 -O2 -o Sol Sol.cpp

if [ $? -eq 0 ]; then
    echo "Compilation done!"
else
    echo "Compilation failed!"
    exit 1
fi

echo "Running Sol ..."
./Sol < input.txt > output.txt

if [ $? -eq 0 ]; then
    echo "Run done!"
    echo "Output:"
    bat output.txt
else
    echo "Execution failed!"
    exit 1
fi

paste the input into input.txt from the site.

in the proper directory, run :

chmod +x run.sh

and then :

./run.sh

save your time.

I wont be accounting the practice round.

Round 1

• started at 22:30 on 5th Oct 24.

Problem A

• read A
• got to implement quickly
• all that was needed was (i + 1) / b[i] and (i + 1) / a[i]
• AC!

Problem B

• read B
• sieve
• precompute upto 1e7 + k
• implemented O(n ^ 2) solution
• passed sample cases
• tle on validation input
• optimized using pre sums

Problem C

• read C
• probability and expectation ?
• tourist’s mint template
• check l == 0
• w - g
• exp = e(x) = e(x₁) * (w - g)
• e(x₁) = 0 … 1 … … (2 * L + 2)
• e(x) = 2 * L + 2 - 1 = 2 * l + 1
• ans = (w - g) * (2L + 1)