Hi,

I’ve been trying to solve Atcoder’s dp problem collection. I started doing a problem called “Grid 1” (https://atcoder.jp/contests/dp/tasks/dp_h) but my solution gave AC on only half of the test cases. Could anyone please help me figure out my mistake?

I’ve defined dp[i][j] as being the total number of ways to reach the i, j position from 0, 0. I’m using 0-based indexing everywhere…

```
h, w = map(int, input().split())
grid = []
for i in range(h):
r = input()
curr = []
for ch in r:
if ch == ".":
curr += [0]
else:
curr += [1]
grid.append(curr)
def outofbounds(i, j):
return (i < 0 or j < 0) or (i >= h or j >= w)
dp = [[None for x in range(w)] for y in range(h)]
dp[0][0] = 1
def recursive(i, j):
if outofbounds(i, j):
return 0
elif dp[i][j] is not None:
return dp[i][j]
elif grid[i][j] == 1:
dp[i][j] = 0
return 0
else:
dp[i][j] = recursive(i-1, j) + recursive(i, j-1)
return dp[i][j]
print(recursive(h-1, w-1))
```