leetcode-1-two-sum

Description

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

1 2	Input: 123 Output: 321

Example 2:

1 2	Input: -123 Output: -321

Example 3:

1 2	Input: 120 Output: 21

Note:

Assume we are dealing with an environment which could only hold integers within the 32-bit signed integer range. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

思路

題意是給妳一個整型數，求它的逆序整型數，而且有個小坑點，當它的逆序整型數溢出的話，那麽就返回 0，用我們代碼表示的話可以求得結果保存在 long 中，最後把結果和整型的兩個範圍比較即可。

class Solution {
    public int reverse(int x) {
        long res = 0;
        for (; x != 0; x /= 10)
            res = res * 10 + x % 10;
        return res > Integer.MAX_VALUE || res < Integer.MIN_VALUE ? 0 : (int) res;
    }
}