題目

Given an integer matrix, find the length of the longest increasing path.

From each cell, you can either move to four directions: left, right, up or down. You may NOT move diagonally or move outside of the boundary (i.e. wrap-around is not allowed).

有點像找單詞的遊戲，忘記叫什麼了

class Solution(object):
    def longestIncreasingPath(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: int
        """
        if not matrix: return 0
        m, n = len(matrix), len(matrix[0])
        dis = [[0 for j in xrange(n)] for i in xrange(m)]
        return max([self.dfs(i, j, m, n, matrix, dis) for j in xrange(n) for i in xrange(m)])
 
    def dfs(self, x, y, m, n, matrix, dis):
        if dis[x][y]: return dis[x][y]
        for dx, dy in ([(1, 0), (-1, 0), (0, 1), (0, -1)]):
            nx, ny = x + dx, y + dy
            if nx >= 0 and nx < m and ny >= 0 and ny < n and matrix[x][y] < matrix[nx][ny]:
                dis[x][y] = max(dis[x][y], self.dfs(nx, ny, m, n, matrix, dis))
        dis[x][y] += 1
        return dis[x][y]