洛谷 python P1434 [SHOI2002] 滑雪

 遍历图，记录中间的计算结果，避免重复计算。

知识点：

• 深度优点搜索
• 记忆化搜索

n, m = map(int, input().split())
nums = []
for i in range(n):
    nums.append(list(map(int, input().split())))
resMatrix = [[0] * m for _ in range(n)]
res = 1
wards = [[-1, 0], [1, 0], [0, -1], [0, 1]]
def dfs(i, j):
    for x, y in wards:
        x += i
        y += j
        if 0 <= x < n and 0 <= y < m and nums[x][y] < nums[i][j]:
            if resMatrix[x][y] == 0:
                dfs(x, y)
            if resMatrix[x][y] > resMatrix[i][j]:
                resMatrix[i][j] = resMatrix[x][y]
    resMatrix[i][j] += 1

for i in range(n):
    for j in range(m):
        if resMatrix[i][j] == 0:
            dfs(i, j)
        if resMatrix[i][j] > res:
            res = resMatrix[i][j]
print(res)