Welcome to decompilation
Decompiling is the art of recovering the original C source from a compiled binary. Here you don't guess — you prove it. You write C, the real Metrowerks CodeWarrior GC/2.0 compiler turns it into PowerPC assembly, and we compare it, instruction for instruction, against the target. When every instruction lines up, you have a 100% match. Even a single extra instruction counts as a mismatch, so small choices like a variable's type matter more than you might expect.
The first piece of PowerPC to know
The GameCube's CPU returns a function's result in register r3. A function that returns an integer constant therefore does just two things:
li r3, 42 # load immediate 42 into r3
blr # branch to link register = "return"
li means load immediate and blr (branch to link register) is how every function returns. You'll see blr at the end of almost everything.
Your task
The target on the right is exactly those two instructions. Write the C function answer that returns 42. Hit Compile & Check (or ⌘/Ctrl + Enter).