求助,Python3第二个点RE

Python3

90分,测试点2RE其余全过,不给下载数据,萌新无力解决问题,又不知道哪里出了问题.求大佬帮忙!

def dfs(nodes, x, y, s):
    for i, j in [(x, y + 1), (x, y - 1), (x + 1, y), (x - 1, y)]:
        has_yield = False
        if 0 <= i < h and 0 <= j < w:
            if nodes[i][j] and nums[i][j] > nums[x][y]:
                nodes[i][j] = 0
                has_yield = True
                yield from dfs(nodes, i, j, s + 1)
                nodes[i][j] = 1
        if not has_yield:
            yield s

h, w = [int(i) for i in input().split()]
nums = [[int(i) for i in input().split()] for _ in range(h)]
paths = [[1 for j in range(w)] for i in range(h)]
ans = max([max(dfs(paths, i, j, 1)) for j in range(w) for i in range(h)])
print(ans)

跪求!