1088: [SCOI2005]扫雷Mine

 1 var
 2    i,j,k,l,m,n:longint;
 3    a,b,c:array[0..20000] of longint;
 4 function doit(x:longint):boolean;
 5          begin
 6               if x>n then
 7                  begin
 8                       if (a[x-1]-b[x-2]-b[x-1])=0 then exit(true) else exit(false);
 9                  end;
10               if ((a[x-1]-b[x-2]-b[x-1])>=0) and ((a[x-1]-b[x-2]-b[x-1])<=1) then
11                  begin
12                       b[x]:=a[x-1]-b[x-2]-b[x-1];
13                       exit(doit(x+1));
14                  end;
15               exit(false);
16          end;
17 begin
18      readln(n);
19      for i:=1 to n do
20          read(a[i]);
21      readln;k:=0;
22      for i:=0 to 1 do
23          for j:=0 to 1 do
24              begin
25                   b[1]:=i;b[2]:=j;
26                   if (b[1]+b[2])=a[1] then
27                      begin
28                           if doit(3) then inc(k);
29                      end;
30              end;
31      writeln(k);