ARTS Week 2

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Week 2

Algorithm

You are given two non-empty linked lists representing two non-negative integers. 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.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.

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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        pre = 0
        first = ListNode(0)
        curr = first
        while(l1 != None) or (l2 != None):
            if l1 == None:
                x = 0
            else:
                x = l1.val
                l1 = l1.next
            if l2 == None:
                y = 0
            else:
                y = l2.val
                l2 = l2.next
            sum = x + y + pre
            mod = sum % 10
            pre = sum // 10
            curr.next = ListNode(mod)
            curr = curr.next
        if pre == 1:
            curr.next=ListNode(1)
        return first.next

Review

imgtool

imgtool工具是包含在《最强Android书：架构大剖析》第三章android启动备份和重置中的工具套件，imgtool能够解析以及提取很多image。这套工具对于研究android的系统镜像提供了很大的帮助。imgtool工具套件提供了Mac OS X和linux的二进制可执行文件和源码。
这套工具可以在你刷机之前，检视这些image，避免被image中恶意软件所害。

Tips

shell 学习第十天—sed 查找与替换

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# 用 shell 命令将 test.log 文件中第 3-5 行的第 2 个“filter”替换成“haha”
sed -i '3,5s/filter/haha/2' test.log

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SED 简明教程
sed有着很的处理的文本的能力，它能够通过强大的正则表达式来对文件进行批量的替换，省去了很多的机械作业。