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329.py
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329.py
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__________________________________________________________________________________________________
sample 372 ms submission
class Solution:
def longestIncreasingPath(self, matrix):
if not matrix: return 0
def dfs(i, j):
if not dp[i][j]:
val = matrix[i][j]
dp[i][j] = 1 + max(
dfs(i - 1, j) if i and val < matrix[i - 1][j] else 0,
dfs(i + 1, j) if i < M - 1 and val < matrix[i + 1][j] else 0,
dfs(i, j - 1) if j and val < matrix[i][j - 1] else 0,
dfs(i, j + 1) if j < N - 1 and val < matrix[i][j + 1] else 0)
return dp[i][j]
M, N = len(matrix), len(matrix[0])
dp = [[0] * N for i in range(M)]
return max(dfs(x, y) for x in range(M) for y in range(N))
__________________________________________________________________________________________________
sample 13312 kb submission
class Solution(object):
def longestIncreasingPath(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: int
"""
if not matrix: return 0
self.directions = [(1,0),(-1,0),(0,1),(0,-1)]
m = len(matrix)
n = len(matrix[0])
cache = [[-1 for _ in range(n)] for _ in range(m)]
res = 0
for i in range(m):
for j in range(n):
cur_len = self.dfs(i, j, matrix, cache, m, n)
res = max(res, cur_len)
return res
def dfs(self, i, j, matrix, cache, m, n):
if cache[i][j] != -1:
return cache[i][j]
res = 1
for direction in self.directions:
x, y = i + direction[0], j + direction[1]
if x < 0 or x >= m or y < 0 or y >= n or matrix[x][y] <= matrix[i][j]:
continue
length = 1 + self.dfs(x, y, matrix, cache, m, n)
res = max(length, res)
cache[i][j] = res
return res
__________________________________________________________________________________________________