Language Details: Lua

Lua is a powerful, fast, lightweight, embeddable scripting language, combining simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics.

Official website (see also: Wikipedia article)
Code Jam 2012 Contestants using Lua
Qualification Round
Used in 63 solutions by 22 contestants:
Round 1A
Used in 11 solutions by 4 contestants:
Round 1B
Used in 2 solutions by 2 contestants:
Round 1C
Used in 2 solutions by 1 contestants:
Round 2
Used in 3 solutions by 1 contestants:

Submission Origin

Canada (4 contestants)
United States (3 contestants)
China (2 contestants)
Russia (2 contestants)
United Kingdom (2 contestants)
Australia (1 contestant)
Brazil (1 contestant)
Denmark (1 contestant)
Finland (1 contestant)
France (1 contestant)
Greece (1 contestant)
Japan (1 contestant)
Singapore (1 contestant)
Spain (1 contestant)
Turkey (1 contestant)