#include<iostream>
using namespace std;
int xb,yb,xm,ym,asd[21][21]={0};//1有障碍
int book[100000][100000]={0};//0未访问
void dfs(int xa,int ya,int w){1. - 1. 
    if(xa==xb&&ya==yb){
    cout<<w;   
    return; }   //边界
    else{
        if(asd[xa+1][ya]==0 && xa<xb && book[xa+1][ya]==0){
            book[xa+1][ya]=1;
            dfs(xa+1,ya,w+1);
            book[xa+1][ya]=0;}
        if(asd[xa][ya+1]==0 && ya<yb && book[xa][ya+1]==0){
            book[xa][ya+1]=1;
            dfs(xa,ya+1,w+1);
            book[xa][ya+1]=0;}
    }

}
int main(){
    cin>>xb>>yb>>xm>>ym;
    if (xm<=18 && ym<=19)asd[xm+2][ym+1]=1;
    if (xm<=19 && ym<=18)asd[xm+1][ym+2]=1;
    if (xm>=1 && ym<=18)asd[xm-1][ym+2]=1;
    if (xm>=2 && ym<=19)asd[xm-2][ym+1]=1;
    if (xm>=2 && ym>=1)asd[xm-2][ym-1]=1;
    if (xm>=1 && ym>=2)asd[xm-1][ym-2]=1;
    if (xm<=19 && ym>=2)asd[xm+1][ym-2]=1;
    if (xm<=18 && ym>=1)asd[xm+2][ym-1]=1;
    dfs(0,0,0);
    return 0;
}

编译结果： No valid executable file was produced by the compiler ./ccbSglIM.o: in function __static_initialization_and_destruction_0(int, int)': src:(.text+0x555): relocation truncated to fit: R_X86_64_PC32 against .bss' src:(.text+0x56e): relocation truncated to fit: R_X86_64_PC32 against `.bss' collect2: 错误：ld 返回 1