Implement is_inserted method to check if string was inserted in Trie. (#517)

Author: sak-codes

pydatastructs/strings/tests/test_trie.py

@@ -2,13 +2,23 @@
 
 def test_Trie():
 
-    strings = ["A", "to", "tea", "ted", "ten", "i", "in", "inn"]
+    strings = ["A", "to", "tea", "ted", "ten", "i",
+               "in", "inn", "Amfn", "snbr"]
     trie = Trie()
     for string in strings:
         trie.insert(string)
 
+    prefix_strings = ["te", "t", "Am", "snb"]
+
     for string in strings:
+        assert trie.is_inserted(string)
+
+    for string in strings[::-1]:
+        assert trie.is_inserted(string)
+
+    for string in prefix_strings:
         assert trie.is_present(string)
+        assert not trie.is_inserted(string)
 
     assert sorted(trie.strings_with_prefix("t")) == ['tea', 'ted', 'ten', 'to']
     assert sorted(trie.strings_with_prefix("te")) == ["tea", "ted", "ten"]
@@ -23,7 +33,17 @@ def test_Trie():
         trie.delete(string)
         for present in strings:
             if present == string:
-                assert not trie.is_present(present)
+                assert not trie.is_inserted(present)
             else:
                 assert trie.is_present(present)
+                assert trie.is_inserted(present)
         strings.remove(string)
+
+    prefix_strings_1 = ["dict", "dicts", "dicts_lists_tuples"]
+    trie_1 = Trie()
+
+    for i in range(len(prefix_strings_1)):
+        trie_1.insert(prefix_strings_1[i])
+        for j in range(i + 1):
+            assert trie_1.is_inserted(prefix_strings_1[j])
+            assert trie_1.is_present(prefix_strings_1[j])

pydatastructs/strings/trie.py

@@ -104,6 +104,28 @@ def is_present(self, string: str) -> bool:
             walk = walk.get_child(char)
         return True
 
+    def is_inserted(self, string: str) -> bool:
+        """
+        Checks if the given string was inserted in the trie.
+
+        Parameters
+        ==========
+
+        string: str
+
+        Returns
+        =======
+
+        True if the given string was inserted in trie;
+        False in all other cases.
+        """
+        walk = self.root
+        for char in string:
+            if walk.get_child(char) is None:
+                return False
+            walk = walk.get_child(char)
+        return walk.is_terminal
+
     def delete(self, string: str) -> bool:
         """
         Deletes the given string from the trie.