TYVJ 1138 Cannot神牛的RP采摘

第一篇文章就弄个水题吧。。

范围太小，DP或者搜索都可以过，就是无解的判断容易弄错。

Code:

var
   f:array [0..201,0..201,0..201] of longint;
   a:array [0..201,0..201] of longint;
   n,m,k,i,j,v,bx,by,ex,ey:longint;
 function max(a,b:longint):longint;
   begin
     if a>b then exit(a) else exit(b);
   end;
 begin
   readln(n,m,k);
   readln(bx,by,ex,ey);
   if abs(ex-bx)+abs(ey-by)>k then
     begin
       writeln('Cannot can''t!');
       exit;
     end;
   for i:=1 to n do
     for j:=1 to m do
       read(a[i,j]);
   for v:=0 to k do
     for i:=0 to n+1 do
       for j:=0 to m+1 do
         f[i,j,v]:=-maxlongint div 2;
   f[bx,by,0]:=0;
   for v:=1 to k do
     for i:=1 to n do
       for j:=1 to m do
         if a[i,j]<>0 then
           f[i,j,v]:=max(
                         max(
                                 max(
                                         f[i,j-1,v-1],
                                         f[i,j+1,v-1]),
                                 max(
                                         f[i-1,j,v-1],
                                         f[i+1,j,v-1]))+a[i,j],
                         f[i,j,v-1])
         else f[i,j,v]:=f[i,j,v-1];
   if f[ex,ey,k]<>-maxlongint div 2
     then writeln(f[ex,ey,k])
     else writeln('Cannot can''t!');
 end.