BTT depth_first_search() implemented

Author: Kishan-Ved

pydatastructs/trees/_backend/cpp/BinaryTreeTraversal.hpp

@@ -7,6 +7,7 @@
 #include <cstdlib>
 #include <iostream>
 #include <stack>
+#include <string>
 #include "../../../utils/_backend/cpp/utils.hpp"
 #include "../../../utils/_backend/cpp/TreeNode.hpp"
 #include "../../../linear_data_structures/_backend/cpp/arrays/ArrayForTrees.hpp"
@@ -42,10 +43,10 @@ static PyObject* BinaryTreeTraversal___new__(PyTypeObject* type, PyObject *args,
 }
 
 static PyObject* BinaryTreeTraversal__pre_order(BinaryTreeTraversal* self, PyObject *args){
+    long node = PyLong_AsLong(PyObject_GetItem(args, PyZero));
     PyObject* visit = PyList_New(0);
     ArrayForTrees* tree = self->tree->tree;
     long size = self->tree->size;
-    long node = PyLong_AsLong(PyObject_GetItem(args, PyZero));
     std::stack<long> s;
     s.push(node);
 
@@ -64,8 +65,29 @@ static PyObject* BinaryTreeTraversal__pre_order(BinaryTreeTraversal* self, PyObj
     return visit;
 }
 
+static PyObject* BinaryTreeTraversal_depth_first_search(BinaryTreeTraversal* self, PyObject *args, PyObject *kwds) {
+    Py_INCREF(Py_None);
+    PyObject* node = Py_None;
+    PyObject* order = PyUnicode_FromString("in_order");
+    static char* keywords[] = {"node","order", NULL};
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OO", keywords, &node, &order)) {
+        return NULL;
+    }
+    if (node == Py_None) {
+        node = self->tree->root_idx;
+    }
+    if (PyUnicode_Compare(order, PyUnicode_FromString("pre_order")) == 0) {
+        return BinaryTreeTraversal__pre_order(self, Py_BuildValue("(O)", node));
+    }
+    else {
+        PyErr_SetString(PyExc_NotImplementedError, "This traversal is not implemented yet or does not exist. Supported traversals: \"pre_order\"");
+        return NULL;
+    }
+}
+
 static struct PyMethodDef BinaryTreeTraversal_PyMethodDef[] = {
     {"_pre_order", (PyCFunction) BinaryTreeTraversal__pre_order, METH_VARARGS, NULL},
+    {"depth_first_search", (PyCFunction) BinaryTreeTraversal_depth_first_search, METH_VARARGS | METH_KEYWORDS, NULL},
     {NULL}
 };
 

pydatastructs/trees/tests/test_binary_trees.py

@@ -60,12 +60,11 @@ def test_cpp_BST2():
     "(5, 6, 6, 6), (None, 4, 4, None), (None, 7, 7, None), (8, 14, 14, None), "
     "(None, 13, 13, None)]")
 
+    ##### BinaryTreeTraversal _pre_order test #####
     from pydatastructs.trees._backend.cpp import _trees
     t = _trees.BinaryTreeTraversal(b)
-    p = t._pre_order(0)
+    p = t.depth_first_search(order="pre_order")
     assert [node.key for node in p] == [8, 3, 1, 6, 4, 7, 10, 14, 13]
-    # key_arr = [node.key for node in p]
-    # print(key_arr)
 
     ##### _simple_path() test #####
     path = b._simple_path(1,0)
@@ -185,7 +184,7 @@ def test_cpp_BST2():
     assert b3.lower_bound(-1) == 7
     assert b3.lower_bound(20) is None
 
-test_cpp_BST2()
+# test_cpp_BST2()
 
 def test_cpp_BST_speed():
     BST = BinarySearchTree