题目
Task
You are at start location [0, 0] in mountain area of NxN and you can only move in one of the four cardinal directions (i.e. North, East, South, West). Return minimal number of climb rounds to target location [N-1, N-1]. Number of climb rounds between adjacent locations is defined as difference of location altitudes (ascending or descending).
Location altitude is defined as an integer number (0-9).
我的答案
from heapq import *
from collections import defaultdict
from math import sqrt, floor
dirc = [[0, 1], [0, -1], [1, 0], [-1, 0]]
def dijkstra(edge, start, N):
heap = []
distance = [-1] * N
distance[start] = 0
heappush(heap, [start, distance[start]])
while len(heap) > 0:
d0 = heappop(heap)[0]
if d0 == N - 1:
return distance[d0]
for i in range(len(edge[d0])):
next = edge[d0][i][0]
l = edge[d0][i][1]
if distance[next] == -1 or distance[d0] + l < distance[next]:
distance[next] = distance[d0] + l
heappush(heap, [next, distance[next]])
return distance[N - 1]
def path_finder(maze):
print(maze)
n = floor(sqrt(len(maze)))
N = n * n
edge = defaultdict(list)
maze = [int(i) for i in list(maze) if i !='\n']
for x in range(n):
for y in range(n):
for i in range(4):
nx = x + dirc[i][0]
ny = y + dirc[i][1]
if nx < 0 or nx >= n or ny < 0 or ny >= n:
continue
d = abs(maze[nx * n + ny] - maze[x * n + y])
edge[x * n + y] += [[nx * n + ny, d]]
return dijkstra(edge, 0, N)
其他精彩答案
def path_finder(maze):
grid = maze.splitlines()
end = h, w = len(grid) - 1, len(grid[0]) - 1
bag, seen = {(0, 0): 0}, set()
while bag:
x, y = min(bag, key=bag.get)
rounds = bag.pop((x, y))
seen.add((x, y))
if (x, y) == end: return rounds
for u, v in (-1, 0), (0, 1), (1, 0), (0, -1):
m, n = x + u, y + v
if (m, n) in seen or not (0 <= m <= h and 0 <= n <= w): continue
new_rounds = rounds + abs(int(grid[x][y]) - int(grid[m][n]))
if new_rounds < bag.get((m, n), float('inf')): bag[m, n] = new_rounds
from heapq import *
def path_finder(maze):
lst = [ [int(c) for c in row] for row in maze.split('\n')]
X, Y = len(lst), len(lst[0])
end = (X-1,Y-1)
q, seens = [(0,end==(0,0),0,0)], {(0,0): 0}
while q and not q[0][1]:
c,_,x,y = heappop(q)
for dx,dy in ((0,1), (0,-1), (1,0), (-1,0)):
new = a,b = x+dx,y+dy
if 0<=a c+dc:
heappush(q, (c+dc, new==end, a, b) )
seens[new] = c+dc
return q[0][0]