View Compilation Error

0_0_24821682_9289.cpp: In function 'void set_table()':
0_0_24821682_9289.cpp:10:10: error: 'i' was not declared in this scope
     for (i=1;i<21;i++) 
          ^
0_0_24821682_9289.cpp: In function 'int main()':
0_0_24821682_9289.cpp:18:10: 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_24821682_9289.cpp:25:9: error: 'i' was not declared in this scope
     for(i=t;i<=n;i++)
         ^