C :

#include<stdio.h>
long  long B[21][21];
 
int main(void)
{
int i,j,n,m,a,b;
scanf("%d%d%d%d",&n,&m,&a,&b);
for(i=0;i<=n;i++)
     for(j=0;j<=m;j++)
         B[i][j]=1;
if(a-2>=0&&b-1>=0)
B[a-2][b-1]=0;   
if(a-2>=0&&b+1<=m) 
B[a-2][b+1]=0;
if(a-1>=0&&b-2>=0)
B[a-1][b-2]=0;
if(a-1>=0&&b+2<=m)
B[a-1][b+2]=0;
if(a+1<=m&&b-2>=0)
B[a+1][b-2]=0;
if(a+2<=n&&b-1>=0)
B[a+2][b-1]=0;
if(a+1<=n&&b+2<=m)
B[a+1][b+2]=0;
if(a+1<=n&&b+1<=m)
B[a+2][b+1]=0;
B[a][b]=0;
for(i=0;i<=n;i++)
{
    for(j=0;j<=m;j++)
    {
        if(B[i][j])
        {
            if(i==0&&j==0) continue;
            else  if(i==0)  B[i][j]=B[i][j-1];
            else if(j==0)   B[i][j]=B[i-1][j];
            else B[i][j]=B[i-1][j]+B[i][j-1]; 
        }
    }
}
printf("%lld",B[n][m]);                /*第一次是用int  后来发现有点小改成long long  之后一直错  上网查了一下下午终于在下午五点发现输出居然用%d！！！ 这道题略坑，我早上11点做到17:55..只是因为这样一个错误。百密一疏呀。*/ 
    return 0;
}

C++ :

#include<iostream>
using namespace std;
long B[21][21];//定义棋盘 

int main(){
	int n,m;//目标点的坐标
	int a,b;//马所在点的坐标
	
	cin>>n>>m>>a>>b;
	
	//初始化棋盘：假设到达目标点(n,m)前每个点都可以通行设置成1
	for(int i=0;i<=n;i++) 
		for(int j=0;j<=m;j++)
			B[i][j]=1;
			
	//将马控制的点设置成0，代表不能通过
	//控制马上边的4个点，只要不超过边届，则为控制点  
	if(a-2>=0&&b-1>=0)  
		B[a-2][b-1]=0; 
		    
	if(a-2>=0&&b+1<=m)   
		B[a-2][b+1]=0; 
		 
	if(a-1>=0&&b-2>=0)  
		B[a-1][b-2]=0; 
		 
	if(a-1>=0&&b+2<=m)  
		B[a-1][b+2]=0; 
	
	//马下边的4个点，只要不超过边届，则为控制点	  
	if(a+1<=n&&b-2>=0)  
		B[a+1][b-2]=0; 
	
	if(a+2<=n&&b-1>=0)  
		B[a+2][b-1]=0;  
		
	if(a+1<=n&&b+2<=m)  
		B[a+1][b+2]=0;  
		
	if(a+1<=n&&b+1<=m)  
		B[a+2][b+1]=0;
	
	//马所在点不能	  
	B[a][b]=0;  
	
	for(int i=0;i<=n;i++){
		for(int j=0;j<=m;j++){
			//如果可行 
			if(B[i][j]){
				
				 if(i==0&&j==0)
				  continue;  
            	 		else if(i==0)  
					B[i][j]=B[i][j-1]; //目标点在最上面一行的时候 
            	 		else if(j==0)  
					 B[i][j]=B[i-1][j];//目标点在最左边一行 
            	 		else 
					B[i][j]=B[i-1][j]+B[i][j-1];//到达目标点路径=上点路径+左点路径 
				
			}
		}
	}
	
	cout<<B[n][m]<<endl;
	 
}

Python :

sr=input().split()
n=int(sr[0])
m=int(sr[1])
x=int(sr[2])
y=int(sr[3])
a=[[1 for i in range(m+1)] for j in range(n+1)]
s=[[1 for i in range(m+1)] for j in range(n+1)]
a[x][y]=0
s[0][0]=1
if(x+2<=n and y+1<=m):
    a[x+2][y+1]=0
if(x+1<=n and y+2<=m):
    a[x+1][y+2]=0
if(x-1>=0 and y+2<=m):
    a[x-1][y+2]=0
if(x-2>=0 and y+1<=m):
    a[x-2][y+1]=0
if(x-2>=0 and y-1>=0):
    a[x-2][y-1]=0
if(x-1>=0 and y-2>=0):
    a[x-1][y-2]=0
if(x+1<=n and y-2>=0):
    a[x+1][y-2]=0
if(x+2<=n and y-1>=0):
    a[x+2][y-1]=0
for i in range(n+1):
    for j in range(m+1):
        if(a[i][j]==0):
            s[i][j]=0
        elif(i>0 and j>0):
            s[i][j]=s[i-1][j]+s[i][j-1]
        elif(i>0):
            s[i][0]=s[i-1][0]
        elif(j>0):
            s[0][j]=s[0][j-1]
print(s[n][m])