BOJ - 1520 - 내리막 길

import sys

def solve(row, column, dp, data, R, C):

    if dp[row][column] == -1:
        dp[row][column] = 0
    else:
        return

    if row - 1 >= 0 and data[row - 1][column] > data[row][column]:
        if dp[row - 1][column] < 0:
            solve(row - 1, column, dp, data, R, C)
        dp[row][column] += dp[row - 1][column]

    if row + 1 < R and data[row + 1][column] > data[row][column]:
        if dp[row + 1][column] < 0:
            solve(row + 1, column, dp, data, R, C)
        dp[row][column] += dp[row + 1][column]

    if column - 1 >= 0 and data[row][column - 1] > data[row][column]:
        if dp[row][column - 1] < 0:
            solve(row, column - 1, dp, data, R, C)
        dp[row][column] += dp[row][column - 1]

    if column + 1 < C and data[row][column + 1] > data[row][column]:
        if dp[row][column + 1] < 0:
            solve(row, column + 1, dp, data, R, C)
        dp[row][column] += dp[row][column + 1]

def solution():
    N, M = map(int, sys.stdin.readline().split())
    data = []
    dp = [[-1 for _ in range(M)] for _ in range(N)]

    dp[0][0] = 1
    for i in range(N):
        data.append(list(map(int, sys.stdin.readline().split())))

    for i in range(N):
        for j in range(M):
            solve(i, j, dp, data, N, M)

    print(dp[-1][-1])
solution()

https://www.acmicpc.net/problem/1520