153 lines
3.9 KiB
Python
153 lines
3.9 KiB
Python
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from pprint import pprint as pp
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import shared
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import matrix
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MATRIX_SIZE = 500
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#MATRIX_SIZE = 40 # sample
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HALF = MATRIX_SIZE // 2
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H = [HALF,HALF]
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T = [HALF,HALF]
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# returns (x,y) - so remember to take dx,dy lower
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DIRS = {
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'U': matrix.M_U, # (0, -1)
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'D': matrix.M_D,
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'L': matrix.M_L,
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'R': matrix.M_R,
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'UR': matrix.M_UR, # (+1, -1)
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'DR': matrix.M_DR,
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'UL': matrix.M_UL,
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'DL': matrix.M_DL,
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}
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def part1(steps):
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field = matrix.matrix_of_size(MATRIX_SIZE,MATRIX_SIZE)
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for direction, amount in steps:
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# move HEAD
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amount = int(amount)
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for x in range(amount):
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dx,dy = DIRS[direction]
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H[0] += dy
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H[1] += dx
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HY,bX = H
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# head is in new position
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kY,kX = T
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field[kY][kX] = 1 # 'T'
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# Check if same
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if kY == HY and kX == bX:
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continue
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touching = False
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for _, d in DIRS.items():
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dx,dy = d
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t_y, t_x = H[0]+dy, H[1]+dx
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if kY == t_y and kX == t_x:
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touching = True
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break
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if touching:
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continue
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# assume the same row/column, no movement needed
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tY = 0
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tX = 0
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# if Head X is less than Tail X, move Tail X 1 left
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if bX < kX:
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tX = -1
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# if Head X is greater than Tail X, move Tail X 1 left
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elif bX > kX:
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tX = 1
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# if Head Y is less than Tail Y, move Tail Y 1 up
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if HY < kY:
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tY = -1
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# if Head Y is greater than Tail Y, move Tail Y 1 down
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elif HY > kY:
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tY = 1
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T[0] += tY
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T[1] += tX
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field[T[0]][T[1]] = 1 # mark visited tails
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print(matrix.sum_matrix(field))
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def part2(steps):
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field = matrix.matrix_of_size(MATRIX_SIZE,MATRIX_SIZE)
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S = [[HALF,HALF],] # HEAD ONLY
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for x in range(9):
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S.append([HALF,HALF])
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for direction, amount in steps:
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# move HEAD
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amount = int(amount)
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for x in range(amount):
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HEAD_dx,HEAD_dy = DIRS[direction]
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S[0][0] += HEAD_dy
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S[0][1] += HEAD_dx
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#print(HEAD_dy,HEAD_dx, S)
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# HEAD MOVED one step
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for knot_idx, _ in enumerate(S):
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if knot_idx == 0:
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# Skip Head
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continue
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knot = S[knot_idx]
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kY,kX = knot
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bY,bX = S[knot_idx-1]
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# Check if same
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if kY == bY and kX == bX:
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continue
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touching = False
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for _, d in DIRS.items():
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dx,dy = d
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t_y, t_x = S[knot_idx-1][0]+dy, S[knot_idx-1][1]+dx
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if kY == t_y and kX == t_x:
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touching = True
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break
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if touching:
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continue
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# assume the same row/column, no movement needed
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tY, tX = 0,0
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# if Head X is less than Tail X, move Tail X 1 left
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if bX < kX:
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tX = -1
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# if Head X is greater than Tail X, move Tail X 1 left
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elif bX > kX:
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tX = 1
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# if Head Y is less than Tail Y, move Tail Y 1 up
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if bY < kY:
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tY = -1
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# if Head Y is greater than Tail Y, move Tail Y 1 down
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elif bY > kY:
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tY = 1
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S[knot_idx][0] += tY
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S[knot_idx][1] += tX
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field[S[-1][0]][S[-1][1]] = 1 # mark visited tails
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print(matrix.sum_matrix(field))
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def main():
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rows = [x.split(" ") for x in shared.load_rows(9)]
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part1(rows)
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part2(rows)
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if __name__ == "__main__":
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main()
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