leetcode 989 数组形式的整数加法

package com.example.lettcode.dailyexercises;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * @Class AddToArrayForm
 * @Description 989 数组形式的整数加法
 * 对于非负整数 X 而言，X 的数组形式是每位数字按从左到右的顺序形成的数组。
 * 例如，如果 X = 1231，那么其数组形式为 [1,2,3,1]。
 * 给定非负整数 X 的数组形式 A，返回整数 X+K 的数组形式。
 * <p>
 * 示例 1：
 * 输入：A = [1,2,0,0], K = 34
 * 输出：[1,2,3,4]
 * 解释：1200 + 34 = 1234
 * <p>
 * 示例 2：
 * 输入：A = [2,7,4], K = 181
 * 输出：[4,5,5]
 * 解释：274 + 181 = 455
 * <p>
 * 示例 3：
 * 输入：A = [2,1,5], K = 806
 * 输出：[1,0,2,1]
 * 解释：215 + 806 = 1021
 * <p>
 * 示例 4：
 * 输入：A = [9,9,9,9,9,9,9,9,9,9], K = 1
 * 输出：[1,0,0,0,0,0,0,0,0,0,0]
 * 解释：9999999999 + 1 = 10000000000
 * 提示：
 * 1 <= A.length <= 10000
 * 0 <= A[i] <= 9
 * 0 <= K <= 10000
 * 如果 A.length > 1，那么 A[0] != 0
 * <p>
 * Related Topics 数组
 * @Author
 * @Date 2021/1/22
 **/
public class AddToArrayForm {

    public static List<Integer> addToArrayForm(int[] A, int K) {
        if (A == null || A.length == 0) return new ArrayList<>(Arrays.asList(K));

        int count = 0;
        List<Integer> integerList = new ArrayList<>();
        for (int i = A.length - 1; i >= 0; i--) {
            int tmp = A[i] + (K % 10) + count;
            integerList.add(tmp % 10);
            K = K / 10;
            count = tmp / 10;
        }
        // 需要考虑数组长度小于整数长度的情况
        while (K != 0) {
            int tmp = K % 10 + count;
            integerList.add(tmp % 10);
            K = K / 10;
            count = tmp / 10;
        }
        List<Integer> resList = new ArrayList<>();
        if (count != 0) resList.add(count);

        for (int i = integerList.size() - 1; i >= 0; i--) {
            resList.add(integerList.get(i));
        }
        return resList;
    }
}

// 测试用例
public static void main(String[] args) {
	int[] A = new int[]{1, 2, 0, 0};
	int K = 34;
	List<Integer> integers = addToArrayForm(A, K);
	System.out.print("AddToArrayForm demo01 result:[");
	for (Integer integer : integers) {
		System.out.print("," + integer);
	}
	System.out.println("]");

	A = new int[]{2, 7, 4};
	K = 181;
	integers = addToArrayForm(A, K);
	System.out.print("AddToArrayForm demo02 result:[");
	for (Integer integer : integers) {
		System.out.print("," + integer);
	}
	System.out.println("]");

	A = new int[]{2, 1, 5};
	K = 806;
	integers = addToArrayForm(A, K);
	System.out.print("AddToArrayForm demo03 result:[");
	for (Integer integer : integers) {
		System.out.print("," + integer);
	}
	System.out.println("]");

	A = new int[]{9, 9, 9, 9, 9, 9, 9, 9, 9, 9};
	K = 1;
	integers = addToArrayForm(A, K);
	System.out.print("AddToArrayForm demo04 result:[");
	for (Integer integer : integers) {
		System.out.print("," + integer);
	}
	System.out.println("]");

	A = new int[]{0};
	K = 23;
	integers = addToArrayForm(A, K);
	System.out.print("AddToArrayForm demo04 result:[");
	for (Integer integer : integers) {
		System.out.print("," + integer);
	}
	System.out.println("]");
}