POJ2329 Nearest number - 2——Dp恶心题
按照从左上开始、从右上开始、从左下开始、从右下开始四个顺序来Dp，记录路径，如果最小路径不唯一那么这个点的权值为0.
极其考察细心和耐心，数据还是比较弱的……
代码：
program poj2329; const maxn=205; var i,j,m,p,q,n :longint; map,f,dp :array[0..maxn,0..maxn]of longint; rec,g :array[0..maxn,0..maxn]of record x,y:longint;end; function min(i,j:longint):longint; begin if i<j then exit(i);exit(j); end; begin readln(n); for i:=1 to n do for j:=1 to n do read(map[i,j]); fillchar(dp,sizeof(dp),127); for i:=1 to n do for j:=1 to n do if map[i,j]<>0 then begin dp[i,j]:=0; rec[i,j].x:=i; rec[i,j].y:=j; end else begin dp[i,j]:=min(dp[i,j-1],dp[i-1,j])+1; if dp[i,j]<maxint then begin if dp[i,j-1]=dp[i-1,j] then begin if (rec[i,j-1].x=rec[i-1,j].x)and(rec[i,j-1].y=rec[i-1,j].y) then rec[i,j]:=rec[i,j-1] else begin rec[i,j].x:=i; rec[i,j].y:=j; end; end else if dp[i,j-1]<dp[i-1,j] then begin if (map[i,j-1]=0)and(rec[i,j-1].x=i)and(rec[i,j-1].y=j-1) then begin rec[i,j].x:=i;rec[i,j].y:=j; end else rec[i,j]:=rec[i,j-1]; end else begin if (map[i-1,j]=0)and(rec[i-1,j].x=i-1)and(rec[i-1,j].y=j) then begin rec[i,j].x:=i;rec[i,j].y:=j; end else rec[i,j]:=rec[i-1,j]; end; end; end; fillchar(f,sizeof(f),127); for i:=1 to n do for j:=1 to n do begin g[i,j].x:=0;g[i,j].y:=0; end; for i:=1 to n do for j:=n downto 1 do if map[i,j]<>0 then begin f[i,j]:=0; g[i,j].x:=i; g[i,j].y:=j; end else begin f[i,j]:=min(f[i,j+1],f[i-1,j])+1; if f[i,j]<maxint then begin if f[i,j+1]=f[i-1,j] then begin if (g[i,j+1].x=g[i-1,j].x)and(g[i,j+1].y=g[i-1,j].y) then g[i,j]:=g[i,j+1] else begin g[i,j].x:=i; g[i,j].y:=j; end; end else if f[i,j+1]<f[i-1,j] then begin if (map[i,j+1]=0)and(g[i,j+1].x=i)and(g[i,j+1].y=j+1) then begin g[i,j].x:=i;g[i,j].y:=j; end else g[i,j]:=g[i,j+1]; end else begin if (map[i-1,j]=0)and(g[i-1,j].x=i-1)and(g[i-1,j].y=j) then begin g[i,j].x:=i;g[i,j].y:=j; end else g[i,j]:=g[i-1,j]; end; end; if f[i,j]<dp[i,j] then begin dp[i,j]:=f[i,j]; rec[i,j]:=g[i,j]; end else if f[i,j]=dp[i,j] then begin if (rec[i,j].x=0)and(rec[i,j].y=0)then rec[i,j]:=g[i,j]; if ((g[i,j].x<>rec[i,j].x)or(g[i,j].y<>rec[i,j].y))and((g[i,j].x<>0)or(g[i,j].y<>0)) then begin rec[i,j].x:=i;rec[i,j].y:=j; end; end; end; fillchar(f,sizeof(f),127); for i:=1 to n do for j:=1 to n do begin g[i,j].x:=0;g[i,j].y:=0; end; for i:=n downto 1 do for j:=n downto 1 do if map[i,j]<>0 then begin f[i,j]:=0; g[i,j].x:=i; g[i,j].y:=j; end else begin f[i,j]:=min(f[i,j+1],f[i+1,j])+1; if f[i,j]<maxint then begin if f[i,j+1]=f[i+1,j] then begin if (g[i,j+1].x=g[i+1,j].x)and(g[i,j+1].y=g[i+1,j].y) then g[i,j]:=g[i,j+1] else begin g[i,j].x:=i; g[i,j].y:=j; end; end else if f[i,j+1]<f[i+1,j] then begin if (map[i,j+1]=0)and(g[i,j+1].x=i)and(g[i,j+1].y=j+1) then begin g[i,j].x:=i;g[i,j].y:=j; end else g[i,j]:=g[i,j+1]; end else begin if (map[i+1,j]=0)and(g[i+1,j].x=i+1)and(g[i+1,j].y=j) then begin g[i,j].x:=i;g[i,j].y:=j; end else g[i,j]:=g[i+1,j]; end; end; if f[i,j]<dp[i,j] then begin dp[i,j]:=f[i,j]; rec[i,j]:=g[i,j]; end else if f[i,j]=dp[i,j] then begin if (rec[i,j].x=0)and(rec[i,j].y=0)then rec[i,j]:=g[i,j]; if ((g[i,j].x<>rec[i,j].x)or(g[i,j].y<>rec[i,j].y))and((g[i,j].x<>0)or(g[i,j].y<>0)) then begin rec[i,j].x:=i;rec[i,j].y:=j; end; end; end; for i:=1 to n do for j:=1 to n do begin g[i,j].x:=0;g[i,j].y:=0; end; fillchar(f,sizeof(f),127); for i:=n downto 1 do for j:=1 to n do if map[i,j]<>0 then begin f[i,j]:=0; g[i,j].x:=i; g[i,j].y:=j; end else begin f[i,j]:=min(f[i,j-1],f[i+1,j])+1; if f[i,j]<maxint then begin if f[i,j-1]=f[i+1,j] then begin if (g[i,j-1].x=g[i+1,j].x)and(g[i,j-1].y=g[i+1,j].y) then g[i,j]:=g[i,j-1] else begin g[i,j].x:=i; g[i,j].y:=j; end; end else if f[i,j-1]<f[i+1,j] then begin if (map[i,j-1]=0)and(g[i,j-1].x=i)and(g[i,j-1].y=j-1) then begin g[i,j].x:=i;g[i,j].y:=j; end else g[i,j]:=g[i,j-1]; end else begin if (map[i+1,j]=0)and(g[i+1,j].x=i+1)and(g[i+1,j].y=j) then begin g[i,j].x:=i;g[i,j].y:=j; end else g[i,j]:=g[i+1,j]; end; end; if f[i,j]<dp[i,j] then begin dp[i,j]:=f[i,j]; rec[i,j]:=g[i,j]; end else if f[i,j]=dp[i,j] then begin if (rec[i,j].x=0)and(rec[i,j].y=0)then rec[i,j]:=g[i,j]; if ((g[i,j].x<>rec[i,j].x)or(g[i,j].y<>rec[i,j].y))and((g[i,j].x<>0)or(g[i,j].y<>0)) then begin rec[i,j].x:=i;rec[i,j].y:=j; end; end; end; for i:=1 to n do begin for j:=1 to n-1 do write(map[rec[i,j].x,rec[i,j].y],' '); writeln(map[rec[i,n].x,rec[i,n].y]); end; end.