One of my favourite quotes about programming is this one:

“ Programming can be fun, so can cryptography; however they should not be combined. ” – Kreitzberg and Shneiderman

Well, there is truth behind this. But on contrary, there is a lot of fun with the combination of the two: the yearly IOCCC contest has posted the 2013 winners!

As in earlier years, it is amazing to see what can be done with creativity and a programming language like C ;-).

Can you tell what this program is doing?

char*_ = "'""/*";
#include 
#define m 21
#define o(l, k) for(l=0; l<k; l++)="" #define="" n(k)="" o(t,="" k)=""              ="" int="" e,l,o,r,g[42][m],h[2][42][m],g[3][8],c="" [42][42][2],f[42];="" char="" d[42];="" void="" v(="" b,int="" a,int="" j){="" printf("\33[%d;%df\33[4%d"="" "m ="" ",a,b,j);="" }="" u(){="" t,e;="" n(42)o(="" e,m)if(h[0][t][e]<span="" class="hiddenSpellError" pre="">-h[1][T][e]){ v(e+4+e,T+2
              ,h[0][T][e]+1?h[0][T][e]:0); h[1][T][e]=h[
              0][T][e]; } fflush(stdout); } void q(int l
                            ,int k,int p){
                            int T,e,a; L=0
                            ; O=1; while(O
                            ){ n(4&&L){ e=
                            k+c[l] [T][0];
                            h[0][L-1+c[l][
                            T][1]][p?20-e:
e]=-1; } n(4){                                          e=k+c[l][T][0]; a=L+c[l][T][
1]+1; if(a==42                                          || h[0][a][p?20-e:e]+1){ O=0
; } } n(4){ e=                                          k+c[l][T][0]; h[0][L + c[l][
T][1]][p?20-e:                                          e]=g[1][f[p?19+l:l]]; } L++;
u(); } n(42) {                                          o(e,m)if(h[0][T][e]<0)break;
o(a, m&&e==m){                                          for(L=T; L; L--) { h[0][L][a
]=h[0][L-1] [a                                          ]; } h[0][0][a]=-1; } } u();
}int main(){ int T,e,t,r,i,s              ,D,V,K; printf("\33[2J\33[?25l"); n(8)g[i=
1][T]=7-T; R--; n(42) o(e,m)              G[T][e]--; while(fgets(d,42,stdin)) { r=++
R; n(17){ e=d[T]-48; d[T]=0;              if ((e&7)==e) { g[0][e] ++; G[R][T+2]=e; }
} } n(8)if(g[0][7-T]){ t=g[i              ][O]; g[i][O++]=g[i][T]; g[i][T]=t; } n(8)
g[2][g[i][T]]=T; n(R+i)o(e,m              )if(G[T][e]+i) G[T][e]=g[2][G[T][e]]; n(19
)o(t,2){ f[T+t+T]=(T["+%#,4"              "5>GP9$5-,#C?NX"]-35)>>t*3&7; o(e,4){ c[T]
[e][t]=("5'<$=$8)Ih$=h9i8'9"              "t=)83)l4(99(g9>##>4(" [T+t+T]-35)>>e*2&3;
} } n(15) { s=T>9?m:(T&3)-3?15:36;o(e,s)o(t,2)c[T+19][e][t]="6*6,8*6.608.6264826668\
865::(+;0(6+6-6/8,61638065678469.;88))()3(6,8*6.608.6264826668865:+;4)-*6-6/616365,\
-6715690.5;,89,81+,(023096/:40(8-7751)2)65;695(855(+*8)+;4**+4(((6.608.626482666886\
5:+;4+4)0(8)6/61638065678469.;88)-4,4*8+4(((60(/6264826668865:+;4-616365676993-9:54\
+-14).;./347.+18*):1;-*0-975/)936.+:4*,80987(887(0(*)4.*""/4,4*8+4(((6264826668865:\
+;4/4-4+8-4)0(8)6365678469.;88)1/(6*6,6.60626466686:8)8-8*818.8582/9863(+;/""*6,6.6\
0626466686:4(8)8-8*818.8582/9863(+;/,6.60626466686:8-818.8582/9864*4+4(0())+;/.6062\
6466686:8/8380/7844,4-4*4+4(0())69+;/0626466686:818582/9864.4/4,4-4*4+4(0())+;" [e+E
+e+t]-40; E+=s+s; } n(45){ if(T>i) { v(2,T,7); v(46,T,7); } v(2+T,44,7); } T=0; o(e,
42)o(t,m)h[T][e][t]--; while(R+i) { s = D=0; if (r-R) { n(19) if (G[R+i][T]+i) V=T/2
; else if(G[R][T]+i) s++; if(s) { if(V>4){ V=9-V; D++; } V+=29; n(20) q(c[V][T][0],c
[V][T][i],D); } } n(19) if((L=G[R][T])+i) { O=T-L; e=O>9; t=e?18-O :O; o(K,((t&3)-3?
16:37)){ if(K){ L=c[t+19][K-i][0]; O=c[t+19][K-i][i] ; } q(L,O,K && e); } } if(s) q(
c[V][20][0], c[V][20][i], D); R--; } printf("\33[47;1f\33[?25h\33[40m"); return 0; }

Solution: It is a painting tool inspired by the ‘Tetris’ idea:

By rotating, positioning and dropping a predetermined sequence of pieces, this program exploits the mechanics of Tetris to generate arbitrary images.

Check out all the details of the submission by Michal Birken. Very well done!

Happy Programming (and de-obfusificating) 🙂