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| 1 | +""" Tries in python |
| 2 | +Methods - insert_key(k, v) |
| 3 | + has_key(k) |
| 4 | + retrie_val(k) |
| 5 | + start_with_prefix(prefix) |
| 6 | +""" |
| 7 | +# HELPERS # |
| 8 | +def _get_child_branches(tr): |
| 9 | + if tr == []: |
| 10 | + return [] |
| 11 | + return tr[1:] |
| 12 | + |
| 13 | +def _get_child_branch(tr, c): |
| 14 | + for branch in _get_child_branches(tr): |
| 15 | + if branch[0] == c: |
| 16 | + return branch |
| 17 | + return None |
| 18 | + |
| 19 | +def _retrive_branch(k, trie_list): |
| 20 | + if k == "": |
| 21 | + return None |
| 22 | + tr = trie_list |
| 23 | + for c in k: |
| 24 | + child_branch = _get_child_branch(tr, c) |
| 25 | + if not child_branch: |
| 26 | + return None |
| 27 | + tr = child_branch |
| 28 | + return tr |
| 29 | + |
| 30 | +def _is_trie_bucket(bucket): |
| 31 | + if len(bucket) != 2: |
| 32 | + return False |
| 33 | + if type(bucket[1]) is tuple: |
| 34 | + return True |
| 35 | + |
| 36 | +def _get_bucket_key(bucket): |
| 37 | + if not _is_trie_bucket(bucket): |
| 38 | + return None |
| 39 | + return bucket[1][0] |
| 40 | + |
| 41 | +# HAS_KEY # |
| 42 | +def has_key(k, tr): |
| 43 | + if k == "": |
| 44 | + return None |
| 45 | + key_tuple = _retrive_branch(k, tr) |
| 46 | + if not key_tuple: |
| 47 | + return False |
| 48 | + return True |
| 49 | + |
| 50 | +# RETRIE_VAL |
| 51 | +def retrie_val(k, tr): |
| 52 | + if k == "": |
| 53 | + return None |
| 54 | + key_tuple = _retrive_branch(k, tr) |
| 55 | + if not key_tuple: |
| 56 | + return None |
| 57 | + return key_tuple[1] |
| 58 | + |
| 59 | + |
| 60 | +def insert_key(key, v, trie_list): |
| 61 | + if key == "": |
| 62 | + return None |
| 63 | + elif has_key(key, trie_list): |
| 64 | + return None |
| 65 | + else: |
| 66 | + tr = trie_list |
| 67 | + for char in key: |
| 68 | + branch = _get_child_branch(tr, char) |
| 69 | + if branch == None: |
| 70 | + new_branch = [char] |
| 71 | + tr.append(new_branch) |
| 72 | + tr = new_branch |
| 73 | + else: |
| 74 | + tr = branch |
| 75 | + tr.append((key, v)) |
| 76 | + return None |
| 77 | + |
| 78 | + |
| 79 | +def start_with_prefix(prefix, trie): |
| 80 | + branch = _retrive_branch(prefix, trie) |
| 81 | + if not branch: |
| 82 | + return [] |
| 83 | + prefix_list = [] |
| 84 | + q = branch[1:] |
| 85 | + while q: |
| 86 | + curr_branch = q.pop(0) |
| 87 | + if _is_trie_bucket(curr_branch): |
| 88 | + prefix_list.append(_get_bucket_key(curr_branch)) |
| 89 | + else: |
| 90 | + q.extend(curr_branch[1:]) |
| 91 | + return prefix_list |
| 92 | + |
| 93 | + |
| 94 | +if __name__ == "__main__": |
| 95 | + trie = [[]] |
| 96 | + states = """ |
| 97 | + Alabama |
| 98 | + Alaska |
| 99 | + Arizona |
| 100 | + Arkansas |
| 101 | + California |
| 102 | + Colorado |
| 103 | + Connecticut |
| 104 | + Delaware |
| 105 | + Florida |
| 106 | + Georgia |
| 107 | + Hawaii |
| 108 | + Idaho |
| 109 | + Illinois |
| 110 | + Indiana |
| 111 | + Iowa |
| 112 | + Kansas |
| 113 | + Kentucky |
| 114 | + Louisiana |
| 115 | + Maine |
| 116 | + Maryland |
| 117 | + Massachusetts |
| 118 | + Michigan |
| 119 | + Minnesota |
| 120 | + Mississippi |
| 121 | + Missouri |
| 122 | + Montana |
| 123 | + Nebraska |
| 124 | + Nevada |
| 125 | + New Hampshire |
| 126 | + New Jersey |
| 127 | + New Mexico |
| 128 | + New York |
| 129 | + North Carolina |
| 130 | + North Dakota |
| 131 | + Ohio |
| 132 | + Oklahoma |
| 133 | + Oregon |
| 134 | + Pennsylvania |
| 135 | + Rhode Island |
| 136 | + South Carolina |
| 137 | + South Dakota |
| 138 | + Tennessee |
| 139 | + Texas |
| 140 | + Utah |
| 141 | + Vermont |
| 142 | + Virginia |
| 143 | + Washington |
| 144 | + West Virginia |
| 145 | + Wisconsin |
| 146 | + Wyoming""" |
| 147 | + states_list = [w.strip().lower() for w in states.splitlines() if w] |
| 148 | + for state in states_list: |
| 149 | + insert_key(state, True, trie) |
| 150 | + print start_with_prefix("new", trie) |
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