Coin is an easy u32 search. Only need to know that when you are earning coins the display shows what you already have coming in and what you earned, you have to subtract away what you already have, after just a few iteration you will be able to have insane amount of coins, no need to make code.
But I decided to make it anyway. Keep in mind that the hack is for the level earned gold. While the code is active what you earn for that level is fixed. While the code is active you will keep earning this much every level you play. Should turn off the code after using it once or you get too much gold.