C :

#include<stdio.h>
 long long a[21][21]={0}, b[21][21]={0};
 long long fangfa(int n,int m,int x,int y)
{
	int i,j;
	a[x][y]=1;
	b[0][0]=1;
	if(x==2&&y==1||x==1&&y==2)
		return 0;
	if(0<=x-2&&x-2<=n&&0<=y-1&&y-1<=m)
		a[x-2][y-1]=1;
	if(0<=x+2&&x+2<=n&&0<=y-1&&y-1<=m)
		a[x+2][y-1]=1;
	if(0<=x-1&&x-1<=n&&0<=y-2&&y-2<=m)
		a[x-1][y-2]=1;
	if(0<=x+1&&x+1<=n&&0<=y-2&&y-2<=m)
		a[x+1][y-2]=1;
	if(0<=x+2&&x+2<=n&&0<=y+1&&y+1<=m)
		a[x+2][y+1]=1;
    if(0<=x-2&&x-2<=n&&0<=y+1&&y+1<=m)
		a[x-2][y+1]=1;
	if(0<=x-1&&x-1<=n&&0<=y+2&&y+2<=m)
		a[x-1][y+2]=1;
	if(0<=x+1&&x+1<=n&&0<=y+2&&y+2<=m)
		a[x+1][y+2]=1;
	for(i=1;i<=n;i++)
		if(a[i][0]==0)
			b[i][0]=b[i-1][0];
		for(j=1;j<=m;j++)
			if(a[0][j]==0)
				b[0][j]=b[0][j-1];
			for(i=1;i<=n;i++)
				for(j=1;j<=m;j++)
				{
					if(a[i][j])
						continue;
					b[i][j]=b[i-1][j]+b[i][j-1];
				}
				return b[n][m];
}
int main()
{
	int n,m,x,y;
	scanf("%d%d%d%d",&n,&m,&x,&y);
	printf("%lld\n",fangfa(n,m,x,y));
	return 0;
}

C++ :

#include <iostream>
using namespace std;
long long dp[25][25]={0};
int dx[9]={0,-1,-2,-2,-1, 1, 2, 2, 1};
int dy[9]={0, 2, 1,-1,-2, 2, 1,-1,-2};
int n,m,x,y;
int main()
{
	cin>>n>>m>>x>>y;
	n+=2; m+=2; x+=2; y+=2;
	for (int i=0;i<9;++i)
		dp[x+dx[i]][y+dy[i]]=-1;
	for (int i=2;i<=n;++i){
		if (dp[i][2]==-1) break;
		dp[i][2]=1;
	}
	for (int i=2;i<=m;++i){
		if (dp[2][i]==-1) break;
		dp[2][i]=1;
	}
	if (dp[2][2]==-1 || dp[n][m]==-1)
		return 0;
	for (int i=3;i<=n;++i)
		for (int j=3;j<=m;++j)
			if (dp[i][j]!=-1){
				if (dp[i-1][j]!=-1) dp[i][j]+=dp[i-1][j];
				if (dp[i][j-1]!=-1) dp[i][j]+=dp[i][j-1];
			}
	cout<<dp[n][m]<<endl;
	return 0;
}

Pascal :

const c:array[1..8]of integer=(1,1,-1,-1,2,2,-2,-2);
      d:array[1..8]of integer=(-2,2,-2,2,1,-1,-1,1);
var b:array[-2..21,-2..21]of boolean;
    i,j,n,m,x,y:integer; f:array[0..21,0..21]of int64;
begin
     readln(n,m,x,y);
    fillchar(b,sizeof(b),true);
    fillchar(f,sizeof(f),0);
    b[x,y]:=false;
    for i:=1 to 8 do
      b[x+c[i],y+d[i]]:=false;
    f[0,0]:=1;
    for i:=1 to m do
      if not b[0,i] then break else f[0,i]:=f[0,i-1];
    for i:=1 to n do
      if not b[i,0] then break else f[i,0]:=f[i-1,0];
    for i:=1 to n do
      for j:=1 to m do
        if b[i,j] then
           f[i,j]:=f[i-1,j]+f[i,j-1];
    writeln(f[n,m]);
end.

Java :

import java.util.Scanner;

public class Main {
    public static final int MAX_N = 25;
    public static int n,m;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        n = scanner.nextInt();
        m = scanner.nextInt();
        int x = scanner.nextInt();
        int y = scanner.nextInt();
        long dp[][] = new long[MAX_N][MAX_N];
        boolean map[][] = new boolean[MAX_N][MAX_N];
        int horseFang[][] ={{2,1},{2,-1},{-2,1},{-2,-1},{1,2},{1,-2},{-1,2},{-1,-2}};
        dp[0][0]=1;
        map[x][y]=true;
        for(int i=0;i<8;i++){//标记控制点
            int xx=x+horseFang[i][0];
            int yy=y+horseFang[i][1];
            if(inMap(xx,yy)){
                map[xx][yy]=true;
            }
        }
        if(map[0][0])//特判
            System.out.println(0);
        for(int i=0;i<=n;i++)
            for(int j=0;j<=m;j++)
                if(!map[i][j]){
                    if(i>=1)
                        dp[i][j]+=dp[i-1][j];
                    if(j>=1)
                        dp[i][j]+=dp[i][j-1];
                }
        System.out.println(dp[n][m]);
    }
    private static boolean inMap(int xx,int yy){
        if(xx<0||yy<0||xx>n||yy>m)
            return false;
        return true;
    }
}
/*
#define MAXN 25
#define LL long long
int mapp[MAXN][MAXN];
LL dp[MAXN][MAXN];
int horseFang[MAXN][2]={2,1,2,-1,-2,1,-2,-1,1,2,1,-2,-1,2,-1,-2};
int x,y,n,m;

bool inMap(int xx,int yy){
    if(xx<0||yy<0||xx>n||yy>m)
        return false;
    return true;
}
void init(){
    memset(dp,0,sizeof(dp));
    memset(mapp,0,sizeof(mapp));
    dp[0][0]=1;
    mapp[x][y]=1;
    for(int i=0;i<8;i++){
        int xx=x+horseFang[i][0];
        int yy=y+horseFang[i][1];
        if(inMap(xx,yy)){
            mapp[xx][yy]=1;
        }
    }
}
void solve(){
    if(mapp[0][0]){
        cout<<0<<endl;
        return;
    }
    for(int i=0;i<=n;i++)
        for(int j=0;j<=m;j++)
            if(!mapp[i][j]){
                if(i>=1)
                    dp[i][j]+=dp[i-1][j];
                if(j>=1)
                    dp[i][j]+=dp[i][j-1];
            }
    cout<<dp[n][m];
}
int main(){
    cin>>n>>m>>x>>y;
    init();
    solve();
    return 0;
}
 */