LeetCode -- Add Two Numbers

標籤：

題目描述：


You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.


Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8


同時遍曆兩個鏈表，對每個節點分別求和，每個節點只存1位結果，保留進位用於下一個節點計算。


思路：
1.兩個指標分別指向鏈表1（l1）和鏈表2（l2）的首位，逐位計算即可。
2.存首節點以及當鏈表遍曆之後，還有carry沒有放入鏈表的情況。

/** * Definition for singly-linked list. * public class ListNode { *     public int val; *     public ListNode next; *     public ListNode(int x) { val = x; } * } */public class Solution {    public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {        ListNode node = null;            ListNode head = null;        var carry = 0;    while(l1 != null || l2 != null){        var a = l1 != null ? l1.val : 0;    var b = l2 != null ? l2.val : 0;        var s = a + b + carry;    var r = s % 10;    if(node == null){    node = new ListNode(r);    head = node;    }else{    node.next = new ListNode(r);    node = node.next;    }    carry = s / 10;        if(l1 != null){    l1 = l1.next;    }    if(l2 != null){    l2 = l2.next;    }    }        if(carry > 0){    var n = new ListNode(carry);    node.next = n;    }        return head;    }}

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LeetCode -- Add Two Numbers