View Compilation Error

0_0_36689645_17832.cpp: In function 'int main()':
0_0_36689645_17832.cpp:33:8: error: 'i' was not declared in this scope
    if (i == 0 && time != 1) //首字符和其后字符相同
        ^
0_0_36689645_17832.cpp:36:12: error: 'i' was not declared in this scope
    s2 = s1[i] + s2; //加入前一个不同的字符
            ^
0_0_36689645_17832.cpp:38:11: error: 's2' was not declared in this scope
   cout << s2 << endl;
           ^
0_0_36689645_17832.cpp: At global scope:
0_0_36689645_17832.cpp:40:2: error: expected unqualified-id before 'return'
  return 0;
  ^
0_0_36689645_17832.cpp:41:1: error: expected declaration before '}' token
 }
 ^