Add alt code to 1989/ovdluhe + update README.md

The alt code is based on the author's remarks. It allows one to more
easily redefine the macro they refer to (P) in a way that lets them try
it out without having to modify the code.

Updated .gitignore.

Format fixes in README.md.

1989/ovdluhe/ovdluhe.alt.c

@@ -0,0 +1,26 @@
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+typedef char ape;
+#define EA register
+#define EP unsigned
+#define A 1
+#define AP (A<<A)
+#ifndef P
+#define P (A<<AP)
+#endif
+#define AE ((P<<P)<<A)
+#define PE (((A<<P)<<P)<<P)
+#define E ((EP)A>>A)
+#define APE {EA EP ape,ea=AE;while(ea--) e[ea]=E;}
+PA();
+;ape a[PE+A],ap,*ae,p[P+A],e[AE];
+main(){ape pe,*ep=a;srand((EP)time((long)E));
+while(((*(ep++)=getchar())!=-A)&&((ep-a)<PE));
+*(ae= --ep)=E;for(ap=E;ap<=P;){APE;if(pe=PA())
+{putchar(pe);if(ap<P){p[ap]=pe;ap++;}else{
+ep=p+A;while(*ep) *(ep-A)= *(ep++); *(ep-A)=pe;}}else break;}}
+PA(){EA ape pe,*ep=a,pa,Ap=E;for(ep=a;ep<ae-P;ep++)
+if(!strncmp(ep,p,ap)){e[*(ep+ap)]++;Ap++;}if(!Ap)return(Ap);
+pa=rand()%Ap+A;pe=~E,Ap=!Ap;while((Ap+=e[++pe])<pa);return(pe);}