/usr/include/flann/ is in libflann-dev 1.7.1-1.
This file is owned by root:root, with mode 0o755.
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/usr/include/flann/algorithms/
/usr/include/flann/algorithms/all_indices.h
/usr/include/flann/algorithms/autotuned_index.h
/usr/include/flann/algorithms/composite_index.h
/usr/include/flann/algorithms/dist.h
/usr/include/flann/algorithms/hierarchical_clustering_index.h
/usr/include/flann/algorithms/kdtree_cuda_3d_index.h
/usr/include/flann/algorithms/kdtree_cuda_builder.h
/usr/include/flann/algorithms/kdtree_index.h
/usr/include/flann/algorithms/kdtree_single_index.h
/usr/include/flann/algorithms/kmeans_index.h
/usr/include/flann/algorithms/linear_index.h
/usr/include/flann/algorithms/lsh_index.h
/usr/include/flann/algorithms/nn_index.h
/usr/include/flann/config.h
/usr/include/flann/defines.h
/usr/include/flann/flann.h
/usr/include/flann/flann.hpp
/usr/include/flann/general.h
/usr/include/flann/io/
/usr/include/flann/io/hdf5.h
/usr/include/flann/mpi/
/usr/include/flann/mpi/client.h
/usr/include/flann/mpi/index.h
/usr/include/flann/mpi/matrix.h
/usr/include/flann/mpi/queries.h
/usr/include/flann/mpi/server.h
/usr/include/flann/nn/
/usr/include/flann/nn/ground_truth.h
/usr/include/flann/nn/index_testing.h
/usr/include/flann/nn/simplex_downhill.h
/usr/include/flann/tbb/
/usr/include/flann/tbb/bodies.hpp
/usr/include/flann/util/
/usr/include/flann/util/allocator.h
/usr/include/flann/util/any.h
/usr/include/flann/util/cuda/
/usr/include/flann/util/cuda/heap.h
/usr/include/flann/util/cuda/result_set.h
/usr/include/flann/util/cutil_math.h
/usr/include/flann/util/dynamic_bitset.h
/usr/include/flann/util/heap.h
/usr/include/flann/util/logger.h
/usr/include/flann/util/lsh_table.h
/usr/include/flann/util/matrix.h
/usr/include/flann/util/object_factory.h
/usr/include/flann/util/params.h
/usr/include/flann/util/random.h
/usr/include/flann/util/result_set.h
/usr/include/flann/util/sampling.h
/usr/include/flann/util/saving.h
/usr/include/flann/util/timer.h