• 问题

Given two sorted arrays nums1 and nums2 of size m and n respectively, return the median of the two sorted arrays.

The overall run time complexity should be O(log (m+n)).

• 代码

class Solution {

    /**
     * @param Integer[] $nums1
     * @param Integer[] $nums2
     * @return Float
     */
    function findMedianSortedArrays($nums1, $nums2) {
        $nums = array_merge($nums1, $nums2);
        $len = count($nums);
        $nums = $this->bubbleSort($nums, $len);

        if ($len % 2) {
            return $nums[floor($len / 2)];
        }

        return ($nums[$len / 2] + $nums[$len / 2 - 1]) / 2;
    }

    function bubbleSort($arr, $n)
    {
        for($i = 0; $i < $n; $i++)
        {
            $swapped = false;
            for ($j = 0; $j < $n - $i - 1; $j++)
            {
                if ($arr[$j] > $arr[$j+1])
                {
                    $t = $arr[$j];
                    $arr[$j] = $arr[$j+1];
                    $arr[$j+1] = $t;
                    $swapped = true;
                }
            }

            if($swapped === false) {
                break;
            }
        }

        return $arr;
    }
}

class Solution
{

    /**
     * @param String $s
     * @return Integer
     */
    public function myAtoi($s)
    {
        $s = ltrim($s);
        if (empty($s)) {
            return 0;
        }

        $ascii = ord($s[0]);
        $sign  = $ascii === 45;
        if ($ascii === 45 || $ascii === 43) {
            $sum = 0;
        } elseif ($ascii >= 48 && $ascii <= 57) {
            $sum = intval($s[0]);
        } else {
            return 0;
        }

        for ($i = 1, $len = strlen($s); $i < $len; ++$i) {
            $ascii = ord($s[$i]);
            if ($ascii < 48 || $ascii > 57) {
                break;
            }

            $sum = $sum * 10 + intval($s[$i]);
        }

        if ($sign) {
            $sum *= -1;
        }

        $boundry = pow(2, 31);
        if ($sum <= -$boundry) {
            return -$boundry;
        } elseif ($sum >= --$boundry) {
            return $boundry;
        }

        return $sum;
    }
}

class Solution {

    /**
     * @param Integer $x
     * @return Boolean
     */
    function isPalindrome($x) {
        if($x >= 0 && $x < 10){
            return true;
        }

        if ($x < 0 || $x % 10 === 0) {
            return false;
        }


        return $this->reverse($x) === $x;
    }

    function reverse($x){
        $sum = 0;
        while($x >= 10){
            $last = $x % 10;
            $x = intval($x / 10);
            $sum = $sum * 10 + $last;
        }

        return $sum * 10 + $x;
    }
}

class Solution
{

    /**
     * @param Integer $x
     * @return Integer
     */
    public function reverse($x)
    {
        if ($x < 10 && $x > -10) {
            return $x;
        }

        $reverse = 0;
        $unsign  = $x >= 0;
        $x       = abs($x);
        do {
            $last    = $x % 10;
            $reverse = $reverse * 10 + $last;
            $x       = intval($x / 10);
        } while ($x >= 10);
        $reverse = $reverse * 10 + $x;
        if (!$unsign) {
            $reverse = -$reverse;

            return $reverse < -(pow(2, 31)) ? 0 : $reverse;
        }

        return $reverse > (pow(2, 31) - 1) ? 0 : $reverse;
    }
}

/*
 * @lc app=leetcode id=6 lang=php
 *
 * [6] ZigZag Conversion
 */

// @lc code=start
class Solution {

    /**
     * @param String $s
     * @param Integer $numRows
     * @return String
     */
    function convert($s, $numRows) {
        $len = strlen($s);
        if ($len === 1 || $numRows === 1) {
            return $s;
        }

        $max = 2 * $numRows - 2;
        
        $str = '';
        // 0 4 8 12
        // 1 3 5 7 9 11 13
        // 2 6 10

        // 0   6    12
        // 1 5 7 11 13
        // 2 4 8 10
        // 3   9    [15]

        // P   H
        // A S I
        // Y I R
        // P L I G
        // A   N
        // 0   8
        // 1 7 9
        // 2 6 10
        // 3 5 11 13
        // 4   12
        
        //ABCDEFGHIJKLMNOPQRSTUVWXYZ
        //A   E   I   M   Q   U   Y
        //B D F H J L N P R T V X Z
        //C   G   K   O   S   W
        //0   4   8    12    16 --- 4
        //1 3 5 7 9 11 13 15 17 --- 2
        //2   6   10   14    18 --- 4
        
        //A   G   M
        //B F H L N R
        //C E I K O Q
        //D   J   P
        //0   6    12    18    6
        //1 5 7 11 13 17 19    4
        //2 4 8 10 14 16 20    2
        //3   9    15    21

        //A   I   Q
        //B H J P R
        //C G K O S
        //D F L N T
        //E   M   U
        //0   8     16    24    8
        //1 7 9  15 17 23 25    6 2 6 2
        //2 6 10 14 18 22       4 4 4 4
        //3 5 11 13 19 21       2 6 2 6
        //4   12    20          8

        //A   K   U
        //B J L T V
        //C I M S W
        //D H N R
        //E G O Q
        //F   P
        //0   10    20   10
        //1 9 11 19 21   8 2 8 2
        //2 8 12 18 22   6 4 6 4
        //3 7 13 17 23   4 6 4 6
        //4 6 14 16 24   2 8 2 8
        //5   15    25   10
        $arr[] = [0, $max];
        $j = 2;
        while($max - $j > 0) {
            $arr[] = [$max - $j, $j];
            $j += 2;
        }
        $arr[] = [0, $max];

        for ($i = 0; $i < $numRows; $i++) {
            $str .= $s[$i];
            $idx = $i;
            while(true) {
                foreach($arr[$i] as $val) {
                    $idx += $val;
                    if($idx >= $len) {
                        break 2;
                    }
                    
                    if (!$val) {
                        continue;
                    }

                    $str .= $s[$idx];
                }
            }
        }

        return $str;
    }
}
// @lc code=end

• 问题

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

• leetcode类别

中等

• 代码

class Solution {

    /**
     * @param String $s
     * @return Integer
     */
    function lengthOfLongestSubstring($s) {
        $len1 = strlen($s);
        if (!$len1) {
            return $len1;
        }

        $max = 1;
        $p = [];
        for($i = 0, $j = 0; $i < $len1; $i++) {
            $code = ord($s[$i]);
            if (!array_key_exists($code, $p)) {
                $p[$code] = $i;
                continue;
            }
            
            $strlen = $i - $j;
            $max = $strlen > $max ? $strlen : $max;
            $i = $p[$code];
            $j = $i + 1;
            $p = [];
        }
        
        $cnt = count($p);
        $max = $cnt > $max ? $cnt : $max;
        
        return $max;
    }
}

• 问题

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

• leetcode类别

中等

• 代码

/**
 * Definition for a singly-linked list.
 * class ListNode {
 *     public $val = 0;
 *     public $next = null;
 *     function __construct($val = 0, $next = null) {
 *         $this->val = $val;
 *         $this->next = $next;
 *     }
 * }
 */
class Solution {

    /**
     * @param ListNode $l1
     * @param ListNode $l2
     * @return ListNode
     */
    function addTwoNumbers($l1, $l2) {
        return $this->reverseList($this->getNode($l1, $l2));
    }

    function reverseList($list) {
        $prev = null;
        while($list !== null) {
            $node = new ListNode($list->val, null);
            $node->next = $prev;

            $prev = $node;
            $list = $list->next;
        }

        return $node;
    }

    function getNode($l1, $l2) {
        $prev = null;
        $plus = 0;
        
        while(true) {
            if ($l1 === null && $l2 === null && !$plus) {
                break;
            }

            $val = 0;
            if ($l1 !== null) {
                $val += $l1->val;
            }

            if ($l2 !== null) {
                $val += $l2->val;
            }

            $val += $plus;

            $plus = 0;
            if ($val > 9) {
                $val = $val % 10;
                $plus = 1;
            }
            
            $node = new ListNode($val, null);
            $node->next = $prev;

            $prev = $node;
            
            if ($l1 !== null) {
                $l1 = $l1->next;
            }

            if ($l2 !== null) {
                $l2 = $l2->next;
            }
        }

        return $node;
    }
}

• 问题

Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

You can return the answer in any order.

• leetcode类别

简单

• 代码

class Solution {

    /**
     * @param Integer[] $nums
     * @param Integer $target
     * @return Integer[]
     */
    function twoSum($nums, $target) {
        $len = count($nums);

        for ($i = 0; $i < $len - 1; ++$i) {
            $sub = $target - $nums[$i];
            for ($j = $i + 1; $j < $len; ++$j) {
                if ($nums[$j] === $sub) {
                    return [$i, $j];
                }
            }
        }

        return [];
    }
}

Elasticsearch在启动时出现错误：

max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

这个问题是虚拟内存设置问题。在虚拟内存有说明：Elasticsearch默认使用mmapfs类型存储文档。对mmapfs的介绍，Elasticsearch文档也有说明。系统默认是65530，对Elasticsearch远远不够。

• 解决办法

修改/etc/sysctl.conf，如果文件内有vm.max_map_count项，那么修改值大于或等于报错值262144。如果没有，在末尾追加一行。

修改完之后再终端执行sysctl --system或者sysctl -p使修改生效。检查是否生效可以使用sysctl vm.max_map_count查看。

在vagrant中增加磁盘空间，可以使用插件vagrant-disksize。

• 插件安装

vagrant plugin install vagrant-disksize

如果出现超时错误，需要终端设置代理。安装好之后，如果虚拟机已经在运行，先使用vagrant halt关闭，在Vagrantfile中添加配置：

config.disksize.size = '50GB'

保存后再使用vagrant up启动。启动时，看到一段话：

==> machine5: Resized disk: old 10240 MB, req 51200 MB, new 51200 MB
==> machine5: You may need to resize the filesystem from within the guest.

• 配置

启动后进入系统，使用df查看发现，磁盘空间没有还是变化。需要下面几个步骤：

1. 运行sudo cfdisk /dev/sda，这时候能够看到新增的空间了。如我的原本是10GB，配置里改为了50GB，这里就看到两行，第一行是/dev/sda1有10GB，第二行是新增的40GB。
2. 使用上下箭头选中第一行，再使用左右箭头选中Resize，后面的提示New size: 50G按回车确认。
3. 再使用左右箭头选择Write，显示提示Are you sure you want to write the partition table to disk?时输入yes按回车确认。
4. 选择Quit回车。
5. 运行sudo resize2fs -p -F /dev/sdaX，X替换为自己对应的数字。如果是centos 7,8这里会提示：resize2fs: Bad magic number in super-block while trying to open /dev/sda1. Couldn't find valid filesystem superblock.换成运行xfs_grows /dev/sda1

最后，使用df查看，磁盘空间已经增加。