bfs水过就好...
type rec=record x,y:longint; end; const walk:array[1..4,1..2] of longint=((1,0),(-1,0),(0,1),(0,-1)); maxn=500; minn=-500; var n,stx,sty,x,y :longint; i :longint; vis,map :array[-505..505,-505..505] of boolean; que :array[0..1000010] of rec; dis :array[-505..505,-505..505] of longint; procedure bfs; var h,tl,curx,cury,cur:longint; k,tx,ty:longint; begin h:=0; tl:=1; que[1].x:=0; que[1].y:=0; dis[0,0]:=0; vis[0,0]:=true; while (h<>tl) do begin h:=h mod 1000005+1; curx:=que[h].x; cury:=que[h].y; cur:=dis[curx,cury]; for k:=1 to 4 do begin tx:=curx+walk[k,1]; ty:=cury+walk[k,2]; if (tx>minn) and (tx<=maxn) and (ty>minn) and(ty<=maxn) then if not map[tx,ty] and not vis[tx,ty] then begin vis[tx,ty]:=true; tl:=tl mod 1000005+1; que[tl].x:=tx; que[tl].y:=ty; dis[tx,ty]:=cur+1; if (tx=stx) and (ty=sty) then exit; end; end; end; end; begin read(stx,sty,n); for i:=1 to n do begin read(x,y); map[x,y]:=true; end; bfs; writeln(dis[stx,sty]); end. ——by Eirlys