| 反转 一个整数意味着倒置它的所有位。 例如，反转 2021 得到 1202 。反转 12300 得到 321 ，不保留前导零 。 给你一个整数 num ，反转 num 得到 reversed1 ，接着反转 reversed1 得到 reversed2 。如果 reversed2 等于 num ，返回 true ；否则，返回 false 。
示例 1： 输入：num = 526 输出：true 解释：反转 num 得到 625 ，接着反转 625 得到 526 ，等于 num 。 示例 2： 输入：num = 1800 输出：false 解释：反转 num 得到 81 ，接着反转 81 得到 18 ，不等于 num 。 示例 3： 输入：num = 0 输出：true 解释：反转 num 得到 0 ，接着反转 0 得到 0 ，等于 num 。
提示： 0 <= num <= 106 来源：力扣（LeetCode） 链接：https://leetcode-cn.com/problems/a-number-after-a-double-reversal 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。 |
| package cn.fansunion.leecode.isNumber; import java.util.List; import cn.fansunion.leecode.kit.Kit; public class ANumberAfterADoubleReversal {
public boolean isSameAfterReversals(int num) { if (num == 0) { return true; } return num % 10 != 0; } public boolean isSameAfterReversals2(int num) { if (num >= 0 && num <= 9) { return true; } List List List int num2 = Kit.digitListToInt(reverseList2); return num == num2; } } |
| package cn.fansunion.leecode.kit; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.Set; public class Kit {
public static void print(int[] array) { if (array == null) { System.out.println("The array is null"); return; } if (array.length == 0) { System.out.println("The array length is 0"); return; } for (int index = 0; index < array.length; index++) { System.out.print(array[index]); if (index != array.length - 1) { System.out.print(","); } else { System.out.println(); } } } public static int[] setToArray(Set int[] nums = new int[set.size()]; int index = 0; for (Integer num : set) { nums[index] = num; index++; } return nums; }
public static List List while (n >= 10) { numList.add(0, n % 10); n = n / 10; } numList.add(0, n); return numList; }
public static List // 取模取余 List // >=10 while (n >= 10) { list.add(n % 10); n = n / 10; } list.add(n); return list; } public static void main(String[] args) { System.out.println(Kit.intToDigitList(1234)); System.out.println(Kit.intToDigitListDesc(1234)); }
public static int digitListToInt(List int num = 0; for (int index = numList.size() - 1; index >= 0; index--) { final int curDigit = numList.get(index); final int time = numList.size() - 1 - index; num += curDigit * Math.pow(10, time); } return num; } public static int digitArrayToInt(int[] numArray) { List for (int num : numArray) { numList.add(num); } return digitListToInt(numList); }
public static List if (numList == null || numList.size() == 1) { return numList; } List for (int index = numList.size() - 1; index >= 0; index--) { reverseList.add(numList.get(index)); } return reverseList; }
public static List List List return list; }
private static List // 找到第1个非0的index int firstNotZeroIndex = -1; for (int index = 0; index < reverseList.size(); index++) { int num = reverseList.get(index); // 非前导0，才保留 if (num != 0) { firstNotZeroIndex = index; break; } } if (firstNotZeroIndex == -1) { return Arrays.asList(0); } List return list; } } |
| package test.leecode.isNumber; import org.junit.Assert; import org.junit.Test; import cn.fansunion.leecode.isNumber.ANumberAfterADoubleReversal; public class ANumberAfterADoubleReversalTest { @Test public void test() { ANumberAfterADoubleReversal test = new ANumberAfterADoubleReversal(); //one Assert.assertTrue(test.isSameAfterReversals(1)); Assert.assertTrue(test.isSameAfterReversals(2)); Assert.assertTrue(test.isSameAfterReversals(9)); Assert.assertTrue(test.isSameAfterReversals(0)); //two Assert.assertTrue(test.isSameAfterReversals(11)); Assert.assertTrue(test.isSameAfterReversals(12)); Assert.assertTrue(test.isSameAfterReversals(78)); Assert.assertFalse(test.isSameAfterReversals(10)); Assert.assertFalse(test.isSameAfterReversals(30)); //three Assert.assertFalse(test.isSameAfterReversals(180)); Assert.assertTrue(test.isSameAfterReversals(181)); Assert.assertTrue(test.isSameAfterReversals(526)); Assert.assertTrue(test.isSameAfterReversals(123)); //four Assert.assertFalse(test.isSameAfterReversals(1800)); Assert.assertTrue(test.isSameAfterReversals(1801)); // Assert.assertTrue(test.isSameAfterReversals(180258941)); Assert.assertFalse(test.isSameAfterReversals(180258940)); }
@Test public void test2() { ANumberAfterADoubleReversal test = new ANumberAfterADoubleReversal(); //one Assert.assertTrue(test.isSameAfterReversals2(1801)); Assert.assertTrue(test.isSameAfterReversals2(1)); Assert.assertTrue(test.isSameAfterReversals2(2)); Assert.assertTrue(test.isSameAfterReversals2(9)); Assert.assertTrue(test.isSameAfterReversals2(0)); //two Assert.assertTrue(test.isSameAfterReversals2(11)); Assert.assertTrue(test.isSameAfterReversals2(12)); Assert.assertTrue(test.isSameAfterReversals2(78)); Assert.assertFalse(test.isSameAfterReversals2(10)); Assert.assertFalse(test.isSameAfterReversals2(30)); //three Assert.assertFalse(test.isSameAfterReversals2(180)); Assert.assertTrue(test.isSameAfterReversals2(181)); Assert.assertTrue(test.isSameAfterReversals2(526)); Assert.assertTrue(test.isSameAfterReversals2(123)); //four Assert.assertFalse(test.isSameAfterReversals2(1800));
// Assert.assertTrue(test.isSameAfterReversals2(180258941)); Assert.assertFalse(test.isSameAfterReversals2(180258940)); } } |
