Advent of Code Leaderboard 2024 / Day 12

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Leaderboard

	Name	Language	Tokens Sum	Tokens Part 1	Tokens Part 2	Last change
1	Michael Böiers	Kotlin	10215	215	-	9 days ago
2	dbasden	C	10344	344	-	9 days ago
3	Mechazawa	Rust	11183	1183	-	9 days ago

Rules

You're welcome to participate alone or in a team.
You may submit multiple solutions and explore different programming languages.
Stick to the standard library of your language, no further dependencies/libraries, except the ones which OneCompiler provides (e.g. NumPy for Python).
Ensure your code aligns to the template (Python, Rust, Go, Kotlin, JavaScript, C#, TypeScript, C++, Java, C, Swift, Scala, Ruby, Bash), reading the puzzle input from stdin (terminated with end-of-file), and printing the solution to stdout.
Please refrain from making network requests, reading data from files, or storing data in variable/function/class names for reflection.
Your code must be able to process all valid Advent of Code inputs. Golfcoder might reevaluate correctness of your solution with different inputs after your submission.

344 tokens in C for part 1 by dbasden

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#include<stdio.h>

chargrid[40960];
intreplanted_grid[40960];
inti,j,width;
longinttotal;

intarea[1024],perimeter[1024];

staticvoidreplant(intpos,intfrom,intto){
if(grid[pos]!=from)return;
replanted_grid[pos]=to;
grid[pos]+=32;
replant(pos-144,from,to);replant(pos-1,from,to);
replant(pos+144,from,to);replant(pos+1,from,to);
}
staticintreplant_everything(){
intnext_colour=1;
for(i=145;i<40815;++i){
intch=grid[i];
if(ch>='A'&&ch<='Z')replant(i,ch,next_colour++);
}
returnnext_colour;
}

intmain(){
char*p=&(grid[1]);
while(scanf("%s%n",(char*)(p+=144),&width)==1);
intmax_ch=replant_everything();
for(i=144+1;i<40960-144-1;++i){
intch=replanted_grid[i];
if(replanted_grid[i]){
area[ch]++;
perimeter[ch]+=(replanted_grid[i-144]!=ch)+(replanted_grid[i-1]!=ch)+(replanted_grid[i+144]!=ch)+(replanted_grid[i+1]!=ch);
}
}
for(intch=1;ch<max_ch;ch++)if(area[ch])total+=area[ch]*perimeter[ch];
printf("%ld\n",total);
}