牛客网：反转数字

/**
 * @author xienl
 * @description 反转数字
 * @date 2022/7/6
 */

public class Solution {
    public static void main(String[] args) {
        Solution solution = new Solution();
        System.out.println(solution.reverse(12));
    }

    /**
     * 转成字符串再转回来，有点耗时
     * @param x
     * @return
     */
    public int reverse (int x) {
        // write code here
        boolean flag = false;
        if (x < 0){
            flag = true;
        }

        String str = Integer.toString(x);
        int n = str.length();
        StringBuffer sb = new StringBuffer();
        if (flag){
            sb.append("-");
        }

        int k = flag ? 1 : 0;
        for (int i = n - 1; i >= k; i--){
            sb.append(str.charAt(i) - '0');
        }
        long l = Long.parseLong(sb.toString());

        return l > Integer.MAX_VALUE || l < Integer.MIN_VALUE ? 0 : (int) l;
    }

}