View Compilation Error

0_0_33894637_21885.cpp:28:9: error: 'shared_ptr' does not name a type
         shared_ptr<Node> ch[2] ;
         ^
0_0_33894637_21885.cpp:75:5: error: 'shared_ptr' does not name a type
     shared_ptr<Node> root ;
     ^
0_0_33894637_21885.cpp: In member function 'void KDTree<K, type>::build(KDTree<K, type>::Point*, int, int)':
0_0_33894637_21885.cpp:65:9: error: 'root' was not declared in this scope
         root.reset(build(points, begin, end, 0)) ;
         ^
0_0_33894637_21885.cpp: In member function 'std::priority_queue<KDTree<K, type>::QNode>& KDTree<K, type>::search(KDTree<K, type>::Point&, int)':
0_0_33894637_21885.cpp:70:23: error: 'root' was not declared in this scope
         search(point, root.get(), m, 0) ;
                       ^