/usr/include/geos/noding/ is in libgeos++-dev 3.5.0-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/geos/noding/BasicSegmentString.h
/usr/include/geos/noding/FastNodingValidator.h
/usr/include/geos/noding/FastSegmentSetIntersectionFinder.h
/usr/include/geos/noding/GeometryNoder.h
/usr/include/geos/noding/IntersectionAdder.h
/usr/include/geos/noding/IntersectionFinderAdder.h
/usr/include/geos/noding/IteratedNoder.h
/usr/include/geos/noding/MCIndexNoder.h
/usr/include/geos/noding/MCIndexSegmentSetMutualIntersector.h
/usr/include/geos/noding/NodableSegmentString.h
/usr/include/geos/noding/NodedSegmentString.h
/usr/include/geos/noding/Noder.h
/usr/include/geos/noding/NodingValidator.h
/usr/include/geos/noding/Octant.h
/usr/include/geos/noding/OrientedCoordinateArray.h
/usr/include/geos/noding/ScaledNoder.h
/usr/include/geos/noding/SegmentIntersectionDetector.h
/usr/include/geos/noding/SegmentIntersector.h
/usr/include/geos/noding/SegmentNode.h
/usr/include/geos/noding/SegmentNodeList.h
/usr/include/geos/noding/SegmentPointComparator.h
/usr/include/geos/noding/SegmentSetMutualIntersector.h
/usr/include/geos/noding/SegmentString.h
/usr/include/geos/noding/SegmentStringUtil.h
/usr/include/geos/noding/SimpleNoder.h
/usr/include/geos/noding/SingleInteriorIntersectionFinder.h
/usr/include/geos/noding/SinglePassNoder.h
/usr/include/geos/noding/snapround/
/usr/include/geos/noding/snapround/HotPixel.h
/usr/include/geos/noding/snapround/MCIndexPointSnapper.h
/usr/include/geos/noding/snapround/MCIndexSnapRounder.h
/usr/include/geos/noding/snapround/SimpleSnapRounder.h