akari.cをわかりやすくしてみた (see. http://www.ioccc.org/2011/akari/hint.html)

akari.c

// Don Yang  
// <omoikane@uguu.org>  
// <http://uguu.org/>  

#include<stdio.h>

int main(int n,char **m)
{
	FILE *p,*q;
	int A,k,a,r,i;
	char *d = "P%"   "d\n%d\40%d\n%d\n\00wb+",
		 b[1024],
		 y[]="yuriyurarararayuruyuri*daijiken**akkari~n**"
			"/y*u*k/riin<ty(uyr)g,aur,arr[a1r2a82*y2*/u*r{uyu}riOcyurhiyua**rrar+*arayra*="
			"yuruyurwiyuriyurara'rariayuruyuriyuriyu>rarararayuruy9uriyu3riyurar_aBrMaPrOaWy^?"
			"*]/f]`;hvroai<dp/f*i*s/<ii(f)a{tpguat<cahfaurh(+uf)a;f}vivn+tf/g*`*w/jmaa+i`ni("
			"i+k[>+b+i>++b++>l[rb";
	int u;
	
	for(i=0;i<101;i++) {
		y[i*2] ^= "~hktrvg~dmG*eoa+%squ#l2"
				":(wn\"1l))v?wM353{/Y;lgcGp`vedllwudvOK`cct~[|ju {stkjalor(stwvne\"gt\"yogYURUYURI"
				[i]^y[i*2+1]^4;
	}

	// 引数解析
	p=(n>1 && (m[1][0] -'-' || m[1][1]!='\0')) ? fopen(m[1],y+298) : stdin;
	q=(n<3 ||!(m[2][0] -'-' || m[2][1]))       ? stdout            : fopen(m[2],d+14);

	// 入力・出力ファイルがオープンできたか確認
	if(!p || !q) {
		return printf(
		//  "Can ""not\x20open\40%s\40"    ""       "for\40%sing\n",m[!p?1:2],!p?"read":"writ");
			"Can not open %s for %sing\n",
			m[!p?1:2],
			!p ? "read" :"writ"
		);
	}

	for(a=k=u=0;y[u];u=2+u){
		y[k++] = y[u];
	}
	
	if((a=fread(b,1,1024,p)) > 2 && b[0] =='P' &&
			4==sscanf(b,d,&k,& A,&i,&r)&&!(k-6&&k-5)&&r==255)
	{
		u=A;
		if(n>3){
			u++;
			i++;
		}
		fprintf(q,d,k,u>>1,i>>1,r);
		u= k-5 ? 8 : 4;
		k=3;
	} else {
		(u)=+(n+14>17) ? 8 / 4 : 8 *5/ 4;
	}
	
	for(r=i=0;;)
	{
		u*=6;
		u+=(n>3?1:0);
		if(y[u]&01) {
			fputc((r),q);
			
			if(y[u]&16) {
				k=A;
			}

			if(y[u]&2) {
				k--;
			}
			
			if(i==a) {
				i=a=(u)*11&255;
			}

			if(1&&0>=(a=fread(b,1,1024,p))
					&&
					")]i>(w)-;} {                                         /i-f-(-m--M1-0.)<{"[8]
					//       ^ ;(=> ASCIIコードで0x3b)
					==59)
			{
				break;
			}
			
			i=0;
		}
		
		r=b[i++];
		u+=(+8&*(y+u)) ? (10-r?4:2) :
					(y[u]&4) ?
						(k?2:4)
						: 2;
		u=y[u]-(int)'`';
					// ` = 0x60
	}
	
	fclose(p);
	k=fclose(q);
	
	return k--1+(-0x01);
	       // kの戻り値をそのまま返す
}