Landminus creative solution for Split List by veky - python coding challenges

Enable Javascript in your browser and then refresh this page, for a much enhanced experience.

Landminus solution in Creative category for Split List by veky

def split_list(items: list) -> list:
    half = -len(items) // 2
    return items[:-half], items[-half:]

Jan. 5, 2020

Comments:

natter1 on April 5, 2021, 3:15 a.m.
Thanks, very educational! So pythons integer division is a floor division (in contrast to other languages like C++). I also learned that % works differently :)

veky on April 5, 2021, 4:03 a.m.
<blockquote> So pythons integer division is a floor division (in contrast to other languages like C++) </blockquote> Yes, because Python is concerned with being easier for the human, not with being easier for the machine. ;-) You might like to read <a href="http://python-history.blogspot.com/2010/08/why-pythons-integer-division-floors.html">this</a>, from the horse's mouth. :-D <blockquote> I also learned that % works differently :) </blockquote> They are the same operation. A language can make various choices regarding q = x//y and r = x%y, but a language where they don't satisfy <pre class='brush: python'>x == q * y + r </pre> would be a very strange language indeed. :-)

_Chico__5d82cee4f5234e78a5c65e on May 15, 2021, 7:17 p.m.
Again...wOw :-b

veky on May 15, 2021, 7:18 p.m.
yAwn. :-P

_Chico__5d82cee4f5234e78a5c65e on May 15, 2021, 7:19 p.m.
Why not yaWn ? xD

veky on May 15, 2021, 7:34 p.m.
Because your `w`s are lowercase. :-P

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:13 a.m.
Oh man ;-)

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:20 a.m.
YoUr SoLuTiOnS aRe MaKiNg Me BoRiNg

veky on May 16, 2021, 6:20 a.m.
Indeed. So you should do something about it. :-P

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:21 a.m.
Th Same and the same...every solution is toooo good to exist;)

veky on May 16, 2021, 6:22 a.m.
I really think you're missing the point of CiO. You should write your own solutions, not just admire the solutions of others.

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:23 a.m.
Oh. xDD

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:24 a.m.
Ok I’m going to write my own solution for a mission here...which you haven’t solved:p

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:31 a.m.
Here that one for visibilities:(have you solved the mission?): from typing import List, Iterable, Tuple from itertools import product from functools import reduce from copy import deepcopy class Contradiction(Exception): pass class Setting: def init(self, grid): self.nrow = len(grid) self.ncolumn = len(grid[0]) <pre class='brush: python'> self.number_dict = dict() for r, c in product(range(self.n_row), range(self.n_column)): if grid[r][c] != 0: self.number_dict[(r, c)] = grid[r][c] def print(self): print("number_dict", self.number_dict) def _is_within(self, pos): return 0 <= pos[0] < self.n_row and 0 <= pos[1] < self.n_column def proximities(self, pos): dps = [(0, +1), (0, -1), (+1, 0), (-1, 0)] cands = [(pos[0] + dp[0], pos[1] + dp[1]) for dp in dps] return list(filter(self._is_within, cands)) </pre> class State: def init(self, setting): numberdict = setting.numberdict self.white = set(numberdict.keys()) self.black = set() self.uncertain = {(r, c) for r, c in product(range(setting.nrow), range(setting.ncolumn))} - self.white self.setting = setting self.okconstraints = set() <pre class='brush: python'>def print(self): print("white", self.white) print("black", self.black) print("uncertain", self.uncertain) print("ok_constraints", self.ok_constraints) def claim_white(self, pos): if pos in self.white: return False if pos in self.black: raise Contradiction() self.uncertain.remove(pos); self.white.add(pos) return True def claim_black(self, pos): if pos in self.black: return False if pos in self.white: raise Contradiction() self.uncertain.remove(pos); self.black.add(pos) """ A kind of Constraint: * Proximities of \`\`black\`\` must be white. """ for p in self.setting.proximities(pos): self.claim_white(p) return True </pre> def divide4(number, limits): def _inner(remain, values, index=0): if index == 3: assert 0 <= remain if remain <= limits[index]: yield values + (remain, ) else: pass else: for i in range(limits[index] + 1): nvalues = values + (i, ) nremain = remain - i if nremain < 0: break yield from inner(nremain, n_values, index + 1) <pre class='brush: python'>return list(_inner(number, (), index=0)) </pre> def makecands(pos, value, setting): fixedwhites = set(setting.numberdict.keys()) <pre class='brush: python'>dps = [(+1, 0), (-1, 0), (0, +1), (0, -1)] limits = [None] * 4 limits[0] = setting.n_row - (pos[0] + 1) limits[1] = pos[0] limits[2] = setting.n_column - (pos[1] + 1) limits[3] = pos[1] partitions = _divide4(value - 1, limits) cands = list() for partition in partitions: # print("partition", partition, "pos", pos, "limits", limits) white = set() black = set() is_valid = True for dp, limit in zip(dps, partition): for step in range(1, limit + 1): p = pos[0] + dp[0] * step, pos[1] + dp[1] * step white.add(p) # print("p", p, step) assert 0 <= p[0] < setting.n_row and 0 <= p[1] < setting.n_column p = pos[0] + dp[0] * (limit + 1), pos[1] + dp[1] * (limit + 1) if not (0 <= p[0] < setting.n_row and 0 <= p[1] < setting.n_column): pass elif p in fixed_whites: is_valid = False else: black.add(p) if is_valid: cands.append((white, black)) return cands </pre> class NumberConstraint: def init(self, pos, value, setting): self.cands = [] # ``list`` of ``pair``, whites, blacks self.cands = makecands(pos, value, setting) <pre class='brush: python'>def _calc_possible_cands(self, s): def _inner(cand): w, b = cand if w & s.black: return False if b & s.white: return False return True return [cand for cand in self.cands if _inner(cand)] def is_satisfied(self, s): possible_cands = self._calc_possible_cands(s) if not possible_cands: raise Contradiction for cand in possible_cands: w, b = cand if w.issubset(s.white) and b.issubset(s.black): return True return False def deduce(self, s): possible_cands = self._calc_possible_cands(s) if not possible_cands: raise Contradiction common_w = reduce(lambda a, b: a & b, (cand[0] for cand in possible_cands)) for cw in common_w: s.claim_white(cw) common_b = reduce(lambda a, b: a & b, (cand[1] for cand in possible_cands)) for cb in common_b: s.claim_black(cb) </pre> def complete(state, constraints): <pre class='brush: python'>target_constraints = [constraint for c_index, constraint in enumerate(constraints) if c_index not in state.ok_constraints] is_updated = False while True: for constraint in target_constraints: if constraint.deduce(state): is_updated = True if not is_updated: break for c_index, constraint in enumerate(constraints): if c_index in state.ok_constraints: continue if constraint.is_satisfied(state): state.ok_constraints.add(c_index) if len(state.ok_constraints) == len(constraints): uncertain = deepcopy(state.uncertain) for c in uncertain: state.claim_white(c) if not state.uncertain: import numpy as np from scipy.ndimage import label setting = state.setting array = np.zeros(shape=(setting.n_row, setting.n_column)) for pos in state.white: array[pos[0]][pos[1]] = True num_pieces = label(array)[1] if 1 < num_pieces : raise Contradiction() return state </pre> def selector(state, constraints): targetconstraints = [constraint for cindex, constraint in enumerate(constraints) if cindex not in state.okconstraints] return min(targetconstraints, key=lambda c: len(c.calcpossiblecands(state))) def search(state, constraints): state = complete(state, constraints) if not state.uncertain: return state <pre class='brush: python'>pivot_const = selector(state, constraints) possible_cands = pivot_const._calc_possible_cands(state) for cand in possible_cands: n_state = deepcopy(state) for w in cand[0]: n_state.claim_white(w) for b in cand[1]: n_state.claim_black(b) try: return search(n_state, constraints) except Contradiction: pass raise Contradiction() </pre> def visibilities(grid: List[List[int]]) -> Iterable[Tuple[int]]: setting = Setting(grid) #setting.print() <pre class='brush: python'>constraints = [NumberConstraint(pos, value, setting) for pos, value in setting.number_dict.items()] print("#constraints", len(constraints)) state = State(setting) #state.print() state = search(state, constraints) return state.black </pre> def checker(func, grid): result = func([row[:] for row in grid]) BLACK, MOVES = -1, ((-1, 0), (1, 0), (0, -1), (0, 1)) ingrid = lambda i, j: 0 <= i < len(grid) and 0 <= j < len(grid[0]) for item in result: if not (isinstance(item, (tuple, list)) and len(item) == 2 and all(isinstance(n, int) for n in item)): print(f"You should give tuples/lists of 2 ints, not {item}.") return False i, j = item if not ingrid(i, j): print(f"{(i, j)} is outside the grid.") return False if grid[i][j] > 0: print("You can't put a black box on the " f"number {grid[i][j]} at {(i, j)}.") return False if grid[i][j] == BLACK: print(f"You can't put a black box twice at {(i, j)}.") return False for x, y in ((i + di, j + dj) for di, dj in MOVES): if ingrid(x, y) and grid[x][y] == BLACK: # RULE 1 print(f"You can't put a black box at {(x, y)} because " f"there is a box at {(i, j)}, it's too close.") return False grid[i][j] = BLACK from numpy import array from scipy.ndimage import label # Powerful tool. boolarray = array([[n != BLACK for n in row] for row in grid]) numpieces = label(boolarray)[1] if numpieces > 1: # RULE 2 print("White boxes in the grid should not be separated " f"into {numpieces} pieces by black boxes.") return False numbers = ((i, j, n) for i, row in enumerate(grid) for j, n in enumerate(row) if n > 0) for i, j, n in numbers: visibilityfromn = 1 for di, dj in MOVES: x, y = i + di, j + dj while ingrid(x, y) and grid[x][y] != BLACK: visibilityfromn += 1 x, y = x + di, y + dj if visibilityfromn != n: # RULE 3 print(f"The box at {(i, j)} should see " f"{n} boxes, not {visibilityfrom_n}.") return False return True if name == "main": GRIDS = (('5x5', [[0, 0, 4, 0, 6], [0, 6, 0, 0, 0], [0, 0, 0, 0, 0], [0, 0, 0, 5, 0], [6, 0, 7, 0, 0]]), <pre class='brush: python'> ('5x8', [[0, 0, 0, 0, 0, 0, 4, 7], [0, 0, 0, 0, 4, 0, 3, 0], [0, 0, 8, 0, 0, 7, 0, 0], [0, 4, 0, 6, 0, 0, 0, 0], [6, 5, 0, 0, 0, 0, 0, 0]]), ('6x9', [[6, 0, 0, 8, 0, 0, 4, 0, 0], [0, 0, 0, 9, 0, 0, 0, 0, 0], [7, 3, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 7, 8], [0, 0, 0, 0, 0, 2, 0, 0, 0], [0, 0, 9, 0, 0, 8, 0, 0, 12]]), ('8x12', [[0, 0, 0, 2, 0, 0, 6, 0, 0, 0, 0, 0], [0, 5, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0], [0, 6, 0, 0, 0, 13, 0, 0, 0, 10, 0, 0], [0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 8, 6], [8, 3, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0], [0, 0, 9, 0, 0, 0, 5, 0, 0, 0, 7, 0], [0, 0, 0, 0, 0, 7, 0, 0, 0, 0, 10, 0], [0, 0, 0, 0, 0, 13, 0, 0, 7, 0, 0, 0]])) for dim, grid in GRIDS: assert checker(visibilities, grid), f"You failed on the grid {dim}." </pre>

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:33 a.m.
Ok,man that’s not working:-b

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:34 a.m.
I will delete it...

_Chico__5d82cee4f5234e78a5c65e on May 16, 2021, 6:44 a.m.
Wait, THAT’S YOUR FIRST COMMENT(TO ME) WITHOUT A SMILEY!!!CONGRATULATIONS!

ChromeBrainer on May 18, 2021, 4:44 a.m.
I'm familiar with the concept still I didn't get the idea in my mind reverse traversal works

veky on May 18, 2021, 4:46 a.m.
You really should learn to communicate better. Punctuation (commas, periods, question marks) really help. Do you need some kind of assistance?

ChromeBrainer on May 18, 2021, 5:02 a.m.
Nah! I think you didn't get it. right? I'm familiar with reverse slicing concept !! But I didn't get the idea to use it, when it should be used.

veky on May 18, 2021, 5:04 a.m.
Now I get what you're saying, and I'm even more confused. :-D Because there is no <a href="https://www.geeksforgeeks.org/python-reverse-slicing-of-given-string/">reverse slicing</a> here. :-]

ChromeBrainer on May 18, 2021, 5:06 a.m.
traversal

veky on May 18, 2021, 5:10 a.m.
Trying to communicate with you is an exercise in futility. Nothing is reversed (nor traversed:) here. `-half` is, despite the appearance, not a negative number. Look, when I put something in Creative category, it's there for a reason. ;-P

ChromeBrainer on May 18, 2021, 5:20 a.m.
I never noticed -half . I apologies for a pointless conversation.

nilac1878 on Jan. 8, 2022, 1:22 p.m.
tried this and: AssertionError: <module>, 10

veky on Jan. 8, 2022, 2:42 p.m.
I'm not sure I can help you. What does line 10 say?

nilac1878 on Jan. 8, 2022, 7:54 p.m.
line 10 - assert split_list([1, 2, 3, 4, 5, 6]) == [[1, 2, 3], [4, 5, 6]] this code returns tuple <pre class='brush: python'>def split_list(items: list) -> list: half = -len(items) // 2 return items[:-half], items[-half:] if __name__ == '__main__': print("Example:") print(split_list([1, 2, 3, 4, 5, 6])) </pre> Example: ([1, 2, 3], [4, 5, 6])

nilac1878 on Jan. 8, 2022, 7:56 p.m.
so with changes <pre class='brush: python'>return [items[:-half], items[-half:]] </pre> it works well

veky on Jan. 8, 2022, 8:26 p.m.
Meh. It's obvious that the author (@oduvan)'s mother tongue is JS, since in Python, `array` means something completely different. And when people don't know what they're talking about, I decide to ignore them. :-P

117370 on Feb. 3, 2023, 1:11 a.m.
Good idea with -half!

veky on Feb. 3, 2023, 1:20 a.m.
Since // gives me floor, I get ceiling by conjugating it with -.

List, list and list again

0 %

You ClassRoom Demo is Ready With the new tool CheckiO ClassRoom, you will be able to analyze your students' progress, have your own leaderboard, change missions order on the map, and so on.