View Compilation Error

0_0_27123899_31177.cpp: In function 'int main()':
0_0_27123899_31177.cpp:20:17: error: 'j' was not declared in this scope
         while(a[j]==0)/*提升监视哨的位置,j有两种可能的位置*/
                 ^
0_0_27123899_31177.cpp:22:14: error: 'j' was not declared in this scope
         flag=j;
              ^
0_0_27123899_31177.cpp:24:11: error: 'flag' was not declared in this scope
     while(flag>=0) /*输出结果*/
           ^