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"name": "langford_n11__v4_nh",
"problem_type": "langford",
"params": {
"n": 11
},
"prompt": "Construct a Langford sequence L(2,11): a sequence of length 22 containing exactly 2 copies of each integer from 1 to 11, such that the two occurrences of each value v are exactly v+1 positions apart (so copies of 1 are 1 position apart, copies of 2 are 2 positions apart, etc.). Example: L(2,3) has solution [2, 3, 1, 2, 1, 3].\n\nReturn seq as a list of 22 integers in 1..11, or state \"UNSATISFIABLE\" if no such sequence exists.",
"satisfiable": true,
"solution": {
"seq": [
6,
2,
3,
11,
2,
10,
3,
6,
9,
1,
8,
1,
4,
7,
5,
11,
10,
4,
9,
8,
5,
7
]
},
"difficulty": {
"solve_time_ms": 1587.0,
"search_space": 1124000727777607680000,
"num_variables": 22,
"num_constraints": 258,
"num_edges": -1,
"backend": "pycsp",
"solve_tier": "hard",
"solve_pct_global": 87.78,
"solve_pct_type": 31.25
},
"partial_assignment": null
}
|