View Compilation Error

0_0_33789279_22396.cpp: In function 'void set_table()':
0_0_33789279_22396.cpp:13:7: error: 'i' was not declared in this scope
  for (i=1;i<21;i++)  
       ^
0_0_33789279_22396.cpp: In function 'int main()':
0_0_33789279_22396.cpp:22:13: error: 'i' was not declared in this scope
         for(i=0;i<21;i++)  s[i]=i;     // 每循环一次就重新归位每组首元素      
             ^
0_0_33789279_22396.cpp:28:21: error: 'i' was not declared in this scope
                 for(i=t;i<=n;i++)  
                     ^