euler-shortest

Solutions to Project Euler problems, with the goal of solving each problem with the shortest possible C program.

Compile flags

I use clang, but gcc seems to work fine too

• -w flag to avoid warnings
• -lm for math functions

Example:

clang -w -lm problems/problem1.c

Program shortening techniques

• No whitespace
• Global variables, the main function and function parameters default to int, so omit the type
• You can use functions of standard headers without including them
• For loops are your friend; pack everything in them
• Program performance is less important than program length
• The first parameter of main is initialized to 1 (argc with only program name)

Shortening transformations

1000            ==>    1E3               (Others: 999, 0xab)
n != 1          ==>    n ^ 1
!(i == 1)       ==>    !(i - 1)
for(a=1;a;a++)  ==>    for(a=0;a++;)