极客时间算法训练营 Week01

import java.util.ArrayList;import java.util.Arrays;import java.util.List;
class Solution {    public int[] plusOne(int[] digits) {        int length = digits.length;        List<Integer> list = new ArrayList<>(length * 2);        int increment = 1;        for (int i = length - 1; i >= 0; i--) {            int result = digits[i] + increment;            list.add(result % 10);            increment = result / 10;        }        if (increment > 0) {            list.add(increment);        }        int size = list.size();        int[] results = new int[size];        for (int i = 0; i < list.size(); i++) {            results[size - i - 1] = list.get(i);        }        return results;    }}

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode() {} *     ListNode(int val) { this.val = val; } *     ListNode(int val, ListNode next) { this.val = val; this.next = next; } * } */class Solution {    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {        ListNode head = new ListNode();        ListNode cur = head;        while(l1 != null && l2 != null) {            int i1 = l1.val;            int i2 = l2.val;            if(i1 <= i2) {                cur.next = l1;                l1 = l1.next;            } else {                cur.next = l2;                l2 = l2.next;            }            cur = cur.next;        }        if (l1 != null) {            cur.next = l1;        }        if (l2 != null) {            cur.next = l2;        }        return head.next;    }}