instances/costas_array_n11__v1_nh.json

{
  "name": "costas_array_n11__v1_nh",
  "problem_type": "costas_array",
  "params": {
    "n": 11
  },
  "prompt": "Find a Costas array of order 11: place 11 marks on an 11x11 grid, one per row and one per column, such that all 11*(10)/2 displacement vectors (dr, dc) between pairs of marks (with dc > 0) are pairwise distinct.\n\nReturn x as a list of 11 integers in 0..10, where x[c] is the row of the mark in column c (permutation), or state \"UNSATISFIABLE\" if no such array exists.",
  "satisfiable": true,
  "solution": {
    "x": [
      9,
      3,
      8,
      4,
      1,
      0,
      7,
      2,
      5,
      6,
      10
    ]
  },
  "difficulty": {
    "solve_time_ms": 1035.3,
    "search_space": 39916800,
    "num_variables": 11,
    "num_constraints": 12,
    "num_edges": -1,
    "backend": "pycsp",
    "solve_tier": "hard",
    "solve_pct_global": 73.12,
    "solve_pct_type": 61.11
  },
  "partial_assignment": null
}