Reverse Integer

Example1: x = 123, return 321
Example2: x = -123, return -321

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Have you thought about this?

Here are some good questions to ask before coding. Bonus points for you if you have already thought through this!

If the integer's last digit is 0, what should the output be? ie, cases such as 10, 100.

Did you notice that the reversed integer might overflow? Assume the input is a 32-bit integer, then the reverse of 1000000003 overflows. How should you handle such cases?

For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

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注意考虑边界

32位的最大整数是0x7fffffff

32位最小的整数是0x80000000

int reverse(int x){if(x>-10&&x<10) return x;const int max = 0x7fffffff;      const int min = 0x80000000;  long long sum = 0;while(x){sum=sum*10+x%10;if(sum>max || sum <min){return 0;}x/=10;}return sum;}