P1002 [NOIP2002 普及组] 过河卒 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

1.DFS做超时40分

n, m, x, y = map(int,input().split())flag = [[0]*(n+10) for _ in range(m+10)]
maps = [[0]*(n+10) for _ in range(m+10)]
d = [[2,1],[2,-1],[-2,1],[-2,-1],[1,2],[1,-2],[-1,2],[-1,-2],[0,0]]for xx,yy in d:dx = x+xxdy = y+yyif 0<=dx<=n and 0<=dy<=m:maps[dx][dy] = 1flag[0][0] = 1
ans = 0dd = [[0,1],[1,0]]
def dfs(sx,sy):global ansif sx == n and sy == m:ans += 1returnfor xx, yy in dd:dx = sx+xxdy = sy+yyif 0<=dx<=n and 0<=dy<=m:if flag[dx][dy] == 0 and maps[dx][dy] == 0:flag[dx][dy] = 1dfs(dx,dy)flag[dx][dy] = 0dfs(0,0)
print(ans)

 

2.DP做100分

n, m, x, y = map(int,input().split())dp = [[0]*(n+10) for _ in range(m+10)]
flag = [[0]*(n+10) for _ in range(m+10)]
d = [[2,1],[2,-1],[-2,1],[-2,-1],[1,2],[1,-2],[-1,2],[-1,-2]]for xx,yy in d:dx = x+xxdy = y+yyif 0<=dx<=n and 0<=dy<=m:flag[dx][dy] = 1
flag[x][y] = 1
flag[0][0] = 1dp[0][0] = 1
for i in range(n+1):for j in range(m+1):if flag[i][j] == 0:if i == 0:dp[i][j] = dp[i][j-1]else:if j == 0:dp[i][j] = dp[i-1][j]else:dp[i][j] = dp[i-1][j] + dp[i][j-1]print(dp[n][m])