leetcode 7

stringstream和INT_MAX和INT_MIN
 1 class Solution {
 2 public:
 3     int reverse(int x) {
 4     std::stringstream ss;
 5       std::string str,result;
 6       long long answer;
 7        ss<<x;
 8       ss>>str;
 9       int start=0,end;
10       if(str[0]=='-') 
11       {
12           result="-";
13            start=1;
14       }
15       else 
16          result="";
17       end=str.size()-1;
18       for(int i=end;i>=start;i--)
19       result.push_back(str[i]);
20       ss.clear();
21       ss.str("");
22       ss<<result;
23       ss>>answer;
24       if(answer>INT_MAX||answer<INT_MIN)
25       return 0;
26       return answer;
27     }
28 };