Given a string s, return the last substring of s in lexicographical order.
 
Example 1:
Input: "abab"
Output: "bab"
Explanation: The substrings are ["a", "ab", "aba", "abab", "b", "ba", "bab"]. The lexicographically maximum substring is "bab".

Example 2:
Input: "leetcode"
Output: "tcode"

 
Note:

1 <= s.length <= 4 * 10^5
s contains only lowercase English letters.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'class Solution:\n    def lastSubstring(self, s: str) -> str:\n        # Keep track of the candidates for the maximum substring\n        # then compare the next characters of the current candidates\n        # and update the candidates list in which all candidates are equally likely to be the maximum subtring\n        # if the length of the candidates list is equal to 1, then the candidate is the maximum subtstring\n        \n        candidate_indices = list(range(len(s))) # at the start, every substring is a candidate \n        index_offset = 0 # will be used to compare the next characters of the candidates\n        \n        while len(candidate_indices) > 1:  # Loop until we have more than one candidate\n            # Using Python List Comprehension to find the maximum of the next char of the candidate\n            current_max = max([s[candidate + index_offset] for candidate in candidate_indices if candidate + index_offset < len(s)])\n            \n            new_candidates = [] # used to update the candidates list\n            \n            # Find the starting index of the current_max character, i.e., finding the new list of candidates\n            for i, candidate in enumerate(candidate_indices):\n                \n                # if the last char of the previous candidate is the start of the current candidate,\n                # merge them together as one candidate\n                if i > 0 and candidate_indices[i - 1] + index_offset == candidate: \n                    continue # Do not need to add the current candidate as the previous is added\n                \n                if candidate + index_offset > len(s) - 1: # we are out of bounds, need to break the loop\n                    break\n                \n                if s[candidate + index_offset] == current_max: # found the candidate which has the current_max\n                    new_candidates.append(candidate) # append the starting index of the current best candidate\n            \n            candidate_indices = new_candidates # Update the candidates\n            index_offset += 1 # Consider the next character\n        \n        # if we are here, it means we have only one candidate, which is the starting index of the maximum substring \n        return s[candidate_indices[0]:]\n        \n        # TIME and SPACE Complexities: O(n), where n - the length of the string\n            \n\n\n\n#         # The Naive Solution\n#         # Keep track of the maximum string in a separate variable\n#         # Do this for every character at index `i`  in string `s` like the following: s[i:]\n#         # The drawback: string comparison takes O(n) time, and we need to do for every string\n#         # starting with character at index `i`. So the overall time complexity would be\n#         # O(n^2) - which is not good.\n        \n#         max_substring = \\"\\" # max_substring means the last substring in lexicographical order\n        \n#         for i in range(len(s)): # iterate over every character in the string\n#             max_substring = max(s[i:], max_substring) # update the maximum substring if the new subtring is greater\n        \n#         return max_substring # return the maxium substring\n'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'lastSubstring'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 5978