untangle includes using iwyu

algorithms/douglas_peucker.cpp

@@ -28,13 +28,13 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "douglas_peucker.hpp"
 
 #include "../data_structures/segment_information.hpp"
-#include "../util/integer_range.hpp"
 
 #include <boost/assert.hpp>
 #include <osrm/coordinate.hpp>
 
 #include <cmath>
 #include <algorithm>
+#include <iterator>
 
 namespace
 {

algorithms/douglas_peucker.hpp

@@ -28,9 +28,13 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef DOUGLAS_PEUCKER_HPP_
 #define DOUGLAS_PEUCKER_HPP_
 
-#include <stack>
-#include <vector>
+#include "../data_structures/segment_information.hpp"
+
 #include <array>
+#include <stack>
+#include <utility>
+#include <vector>
+
 
 /* This class object computes the bitvector of indicating generalized input
  * points according to the (Ramer-)Douglas-Peucker algorithm.
@@ -39,8 +43,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * bit indicating if the points is present in the generalization.
  * Note: points may also be pre-selected*/
 
-struct SegmentInformation;
-
 static const std::array<int, 19> DOUGLAS_PEUCKER_THRESHOLDS {{
     512440, // z0
     256720, // z1