Reverse digits of an integer.
Example1: x = 123, return 321
Example2: x = -123, return -321
Note:
The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.
反转数字，根据数字的特性
比如 4321的反转 1234 = （（（1*10 + 2 ）*10）+3）*10+ 4
class Solution { public: int reverse(int x) { long long y = 0; int mark = 0; if (x < 0) x = -x,mark = 1; while(x > 0) { y *= 10; y += x % 10; x /= 10; if (y > INT_MAX) return 0; } //cout<<((1<<31) - 1)<<" "<<INT_MAX<<endl; if (mark) return - y; return y; } };
原文：http://www.cnblogs.com/pk28/p/7194177.html