算法：两个单链表生成相加链表

标签（空格分隔）： 算法 0

版本：1作者：陈小默声明：禁止商业，禁止转载

发布于作业部落、SCDN

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题目：假设链表中的每一节点的值都在0~9之间，于是我们可以使用整个链表作为一个整数。
例如：

链表9->3->7和链表6->3相加后得到链表1->0->0->0

解法：我们可以先将两个链表转置，然后从低位到高位依次运算。

一下代码给出了三种实现方式，后一种是前一种的简化

/** *  project:DSA *  Copyright (C) <2016>  <陈小默> * *  This program is free software: you can redistribute it and/or modify *  it under the terms of the GNU General Public License as published by *  the Free Software Foundation, either version 3 of the License, or *  (at your option) any later version. * *  This program is distributed in the hope that it will be useful, *  but WITHOUT ANY WARRANTY; without even the implied warranty of *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the *  GNU General Public License for more details. * *  You should have received a copy of the GNU General Public License *  along with this program.  If not, see <http://www.gnu.org/licenses/>. * *  Created by 陈小默 on 16/11/7. */data class Node(var value: Int, var next: Node?) {    override fun toString(): String {        val builder = StringBuilder().append('[')        var node: Node? = this.next        builder.append(value)        while (node != null) {            builder.append(',').append('\t').append(node.value)            node = node.next        }        return builder.append(']').toString()    }}fun reverseList(list: Node): Node {    var pre: Node? = null    var next: Node? = null    var head: Node? = list    while (head != null) {        next = head.next        head.next = pre        pre = head        head = next    }    return pre!!}fun addList_v1(list1: Node, list2: Node): Node {    var l1: Node? = reverseList(list1)    var l2: Node? = reverseList(list2)    var next: Node? = null    var node: Node?    var head: Node? = null    var carry = false    while (l1 != null && l2 != null) {        var value = l1.value + l2.value        if (carry) value++        carry = value > 9        if (carry) value %= 10        node = Node(value, null)        if (head == null) {            head = node            next = node        } else {            next!!.next = node            next = next.next        }        l1 = l1.next        l2 = l2.next    }    while (l1 != null) {        var value = l1.value        if (carry) value++        carry = value > 9        if (carry) value %= 10        node = Node(value, null)        if (head == null) {            head = node            next = node        } else {            next!!.next = node            next = next.next        }        l1 = l1.next    }    while (l2 != null) {        var value = l2.value        if (carry) value++        carry = value > 9        if (carry) value %= 10        node = Node(value, null)        if (head == null) {            head = node            next = node        } else {            next!!.next = node            next = next.next        }        l2 = l2.next    }    if (carry) {        node = Node(1, null)        next!!.next = node    }    return reverseList(head!!)}fun addList_v2(list1: Node, list2: Node): Node {    var l1: Node? = reverseList(list1)    var l2: Node? = reverseList(list2)    var next: Node?    var head: Node? = null    var carry = 0    while (l1 != null && l2 != null) {        val value = l1.value + l2.value + carry        carry = value / 10        next = head        head = Node(value % 10, next)        l1 = l1.next        l2 = l2.next    }    while (l1 != null) {        val value = l1.value + carry        carry = value / 10        next = head        head = Node(value % 10, next)        l1 = l1.next    }    while (l2 != null) {        val value = l2.value + carry        carry = value / 10        next = head        head = Node(value % 10, next)        l2 = l2.next    }    if (carry == 1) {        next = head        head = Node(1, next)    }    return head!!}fun addList(list1: Node, list2: Node): Node {    var l1: Node? = reverseList(list1)    var l2: Node? = reverseList(list2)    var n: Int    var n1: Int    var n2: Int    var next: Node?    var head: Node? = null    var carry = 0    while (l1 != null || l2 != null) {        n1 = if (l1 != null) l1.value else 0        n2 = if (l2 != null) l2.value else 0        n = n1 + n2 + carry        carry = n / 10        next = head        head = Node(n % 10, next)        l1 = if (l1 != null) l1.next else null        l2 = if (l2 != null) l2.next else null    }    if (carry == 1) {        next = head        head = Node(1, next)    }    return head!!}