I strugeled with the last medium graph exercice of week 3 and I found a solution (thanks to LLM proposal of using Ant colony Algorythm)
Best cost: 2749, Best path: [0, 145, 279, 237, 159, 166, 59, 252, 108, 54, 218, 201, 35, 45, 140, 103, 24, 261, 71, 31, 16, 116, 34, 94, 247, 210, 278, 70, 148, 62, 171, 288, 15, 204, 83, 22, 100, 93, 152, 219, 296, 14, 25, 183, 269, 205, 154, 105, 253, 259, 113, 61, 236, 160, 53, 55, 163, 5, 134, 112, 241, 193, 7, 51, 3, 293, 2, 211, 208, 101, 110, 292, 104, 20, 81, 87, 111, 286, 268, 96, 230, 129, 250, 242, 123, 115, 97, 179, 144, 267, 50, 121, 276, 295, 102, 209, 158, 84, 284, 69, 270, 139, 189, 127, 254, 187, 180, 4, 124, 65, 285, 82, 141, 212, 176, 177, 272, 117, 184, 28, 257, 114, 221, 191, 150, 143, 9, 200, 33, 85, 192, 165, 1, 138, 265, 156, 133, 178, 6, 39, 151, 38, 27, 182, 249, 80, 206, 49, 63, 130, 294, 90, 64, 21, 92, 282, 195, 226, 203, 66, 106, 40, 213, 46, 162, 248, 251, 79, 199, 169, 36, 58, 155, 18, 88, 274, 52, 132, 222, 194, 173, 68, 157, 126, 280, 196, 185, 67, 76, 283, 223, 181, 153, 17, 149, 118, 135, 174, 30, 131, 235, 122, 146, 161, 119, 109, 273, 13, 72, 73, 291, 225, 91, 89, 190, 243, 281, 260, 86, 290, 256, 207, 262, 234, 142, 56, 137, 299, 170, 77, 19, 277, 238, 147, 47, 289, 98, 232, 224, 32, 297, 8, 107, 264, 244, 172, 258, 228, 41, 74, 271, 75, 60, 198, 29, 202, 12, 42, 229, 26, 128, 168, 214, 164, 57, 245, 220, 233, 275, 136, 44, 287, 266, 10, 43, 125, 263, 215, 240, 78, 23, 95, 120, 298, 216, 197, 99, 231, 48, 255, 188, 186, 167, 175, 246, 37, 227, 217, 11, 239, 0]
way better than the one proposed (3855) but unfortunately not in the required time of 1.5s.
Anyway, I was really pleased to follow this course, and I will try to use the good advice to always scrutinize the LLM results.