foo.cc: In function 'void dfs(int, int, int)':
foo.cc:30:10: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
          if(map[px][py]=='*'||(map[px][py]=='D'&&now==t-1))
          ^~
foo.cc:37:11: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
           if(flag)      //此处剪枝非常关键！！！ 
           ^~
foo.cc: In function 'int main()':
foo.cc:45:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&n,&m,&t);
         ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:53:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
            scanf(" %c",&map[i][j]);
            ~~~~~^~~~~~~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。