labs
misc things, brain holes, etc.
straightforward yet shitty code.
mostly runnable on a normal pc within some minutes requiring reasonably large RAM.
123456789.cpp
bruteforce enumeration of Crazy Sequential Representation.
based on expression tree building and memorized subproblem.
supports +-×÷, brackets, power(^), concatenation. features floating point fixing and some pruning.
Numberphile's youtube video: the 10958 problem
needs 2gb ram for the full size problem.
bejeweled.c
how many fields exactly are there are stable in the game Bejeweled?
8×8, 7 colors, no 3 gems of the same color in a row.
based on essential pattern and some combinatorics, also Chinese remainder theory.
needs 5gb ram on the full size problem, you have to use 64-bit compilation.
god2048.cpp
bruteforce enumeration of 3×3 simplified 2048 game tree. (giving only "2" on a random position each turn)
based on expecti-max. the result is you can always get a constant max score.
after computation, you enter a simple inspector.
but still no idea for 4×4.
needs 2×10^9 bytes ram.
cm.g4
parser of mathematic expressions in Chinese language as close to usually spoken.
the hardest part turns out to be the structure of how a single (big) number is read in chinese.
sudoku.c
yet another fast and simple sudoku solver. supports both pure naive top-down order and least-candidate-first strategy (switch via #define).
with full usage of bitwise operations, balancing number of operations and data footprint, it's able to run 2.5G recursions (naive version) per minute on my laptop (i3 M350 2.27Hz, GCC 4.7.2).
try to crack them, prove whether they have no, unique or multiple solutions.
4.....8.5.3..........7......2.....6.....8.4......1.......6.3.7.5..2.....1.4......
..............3.85..1.2.......5.7.....4...1...9.......5......73..2.1........4...9
.....5.8....6.1.43..........1.5........1.6...3.......553.....61........4.........
see my stackoverflow quesion.