Add solution for 1023

.gitignore

@@ -1,5 +1,7 @@
 .gradle/
-gradle/
-gradlew
-gradlew.bat
-
+.DS_Store
+build/
+out/
+.idea/
+*.iml
+*.vscode/

.travis.yml

@@ -1,9 +1,12 @@
 language: java
 
 jdk:
-  - oraclejdk8
+  - oraclejdk9
 
-script: gradle clean build
+before_script:
+- chmod a+x gradlew
+
+script: ./gradlew clean build
 
 notifications:
   email:

CODE_OF_CONDUCT.md

@@ -0,0 +1,46 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable behavior and are expected to take appropriate and fair corrective action in response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, or to ban temporarily or permanently any contributor for other behaviors that they deem inappropriate, threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces when an individual is representing the project or its community. Examples of representing a project or community include using an official project e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event. Representation of a project may be further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be reported by contacting the project team at fishercoder@gmail.com. The project team will review and investigate all complaints, and will respond in a way that it deems appropriate to the circumstances. The project team is obligated to maintain confidentiality with regard to the reporter of an incident. Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good faith may face temporary or permanent repercussions as determined by other members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4, available at [http://contributor-covenant.org/version/1/4][version]
+
+[homepage]: http://contributor-covenant.org
+[version]: http://contributor-covenant.org/version/1/4/

LICENSE.md

@@ -186,7 +186,7 @@
       same "printed page" as the copyright notice for easier
       identification within third-party archives.
 
-   Copyright 2017, fishercoder1534 and contributors.
+   Copyright 2019, fishercoder1534 and contributors.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

build.gradle

@@ -15,9 +15,11 @@ sourceCompatibility = 1.8
 targetCompatibility = 1.8
 
 repositories {
-     maven { url "http://repo.maven.apache.org/maven2" }
+    mavenCentral()
+    maven { url "http://repo.maven.apache.org/maven2" }
 }
 
 dependencies {
+    compile 'com.google.code.gson:gson:2.8.0'
     testCompile group: 'junit', name: 'junit', version:'4.12'
 }

cpp/_1.cpp

@@ -0,0 +1,40 @@
+/**
+1. Two Sum
+
+Given an array of integers, return indices of the two numbers such that they add up to a specific target.
+
+You may assume that each input would have exactly one solution, and you may not use the same element twice.
+
+Example:
+
+Given nums = [2, 7, 11, 15], target = 9,
+
+Because nums[0] + nums[1] = 2 + 7 = 9,
+return [0, 1].
+
+*/
+
+#include <vector>
+#include <unordered_map>
+using namespace std;
+
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        unordered_map<int, int> m;
+        vector<int> result;
+        for(int i = 0; i < nums.size(); i++){
+        // not found the second one
+            if (m.find(nums[i]) == m.end() ) {
+            // store the first one poisition into the second one's key
+                m[target - nums[i]] = i;
+            } else {
+            // found the second one
+                result.push_back(m[nums[i]]);
+                result.push_back(i);
+                break;
+            }
+        }
+        return result;
+    }
+};

cpp/_9.cpp

@@ -0,0 +1,60 @@
+/**
+ * 9. Palindrome Number
+ * 
+ * Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
+
+Example 1:
+
+Input: 121
+Output: true
+Example 2:
+
+Input: -121
+Output: false
+Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
+Example 3:
+
+Input: 10
+Output: false
+Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
+Follow up:
+
+Coud you solve it without converting the integer to a string?
+*/
+
+class Solution1 {
+    /**This is a Java translation, while its Java counterpart could be accepted perfectly, this one failed due to
+     * Char 21: runtime error: signed integer overflow: 746384741 * 10 cannot be represented in type 'int' (solution.cpp)
+    */
+public:
+    bool isPalindrome(int x) {
+        if (x == 0) {
+            return true;
+        } else if (x < 0) {
+            return false;
+        }
+        int tmp = x;
+        int reverse = 0;
+        while (tmp != 0) {
+            reverse *= 10;
+            reverse += tmp % 10;
+            tmp /= 10;
+        }
+        return reverse == x;
+    }
+};
+
+class Solution2 {
+public:
+    bool isPalindrome(int x) {
+        if (x < 0 || (x != 0 && x%10 == 0)) {
+            return false;
+        }
+        int sum = 0;
+        while (x > sum) {
+            sum = sum*10 + x%10;
+            x /= 10;
+        }
+        return (x == sum) || (x == sum/10);
+    }
+};

database/_578.sql

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+--578. Get Highest Answer Rate Question
+--
+--Get the highest answer rate question from a table survey_log with these columns: uid, action, question_id, answer_id, q_num, timestamp.
+--
+--uid means user id; action has these kind of values: "show", "answer", "skip"; answer_id is not null when action column is "answer", while is null for "show" and "skip"; q_num is the numeral order of the question in current session.
+--
+--Write a sql query to identify the question which has the highest answer rate.
+--
+--Example:
+--Input:
+--+------+-----------+--------------+------------+-----------+------------+
+--| uid  | action    | question_id  | answer_id  | q_num     | timestamp  |
+--+------+-----------+--------------+------------+-----------+------------+
+--| 5    | show      | 285          | null       | 1         | 123        |
+--| 5    | answer    | 285          | 124124     | 1         | 124        |
+--| 5    | show      | 369          | null       | 2         | 125        |
+--| 5    | skip      | 369          | null       | 2         | 126        |
+--+------+-----------+--------------+------------+-----------+------------+
+--Output:
+--+-------------+
+--| survey_log  |
+--+-------------+
+--|    285      |
+--+-------------+
+--Explanation:
+--question 285 has answer rate 1/1, while question 369 has 0/1 answer rate, so output 285.
+--Note: The highest answer rate meaning is: answer number's ratio in show number in the same question.
+
+SELECT question_id AS 'survey_log' FROM survey_log GROUP BY question_id ORDER BY
+COUNT(answer_id) / COUNT(case when survey_log.action =
+ 'show' then survey_log.action else null end) DESC LIMIT 0,1

database/_603.sql

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+--603. Consecutive Available Seats
+--
+--Several friends at a cinema ticket office would like to reserve consecutive available seats.
+--Can you help to query all the consecutive available seats order by the seat_id using the following cinema table?
+--
+--| seat_id | free |
+--|---------|------|
+--| 1       | 1    |
+--| 2       | 0    |
+--| 3       | 1    |
+--| 4       | 1    |
+--| 5       | 1    |
+--Your query should return the following result for the sample case above.
+--| seat_id |
+--|---------|
+--| 3       |
+--| 4       |
+--| 5       |
+--Note:
+--The seat_id is an auto increment int, and free is bool ('1' means free, and '0' means occupied.).
+--Consecutive available seats are more than 2(inclusive) seats consecutively available.
+
+select c.seat_id from cinema c where c.free = 1
+and
+(
+    c.seat_id+1 in (select seat_id from cinema where free=1)
+    or
+    c.seat_id-1 in (select seat_id from cinema where free=1)
+)
+order by c.seat_id

database/_626.sql

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+--626. Exchange Seats
+--
+--Mary is a teacher in a middle school and she has a table seat storing students' names and their corresponding seat ids.
+--
+--The column id is continuous increment.
+--Mary wants to change seats for the adjacent students.
+--Can you write a SQL query to output the result for Mary?
+--+---------+---------+
+--|    id   | student |
+--+---------+---------+
+--|    1    | Abbot   |
+--|    2    | Doris   |
+--|    3    | Emerson |
+--|    4    | Green   |
+--|    5    | Jeames  |
+--+---------+---------+
+--For the sample input, the output is:
+--+---------+---------+
+--|    id   | student |
+--+---------+---------+
+--|    1    | Doris   |
+--|    2    | Abbot   |
+--|    3    | Green   |
+--|    4    | Emerson |
+--|    5    | Jeames  |
+--+---------+---------+
+--Note:
+--If the number of students is odd, there is no need to change the last one's seat.
+
+
+SELECT
+    (CASE
+        WHEN MOD(id, 2) != 0 AND counts != id THEN id + 1
+        WHEN MOD(id, 2) != 0 AND counts = id THEN id
+        ELSE id - 1
+    END) AS id,
+    student
+FROM
+    seat,
+    (SELECT
+        COUNT(*) AS counts
+    FROM
+        seat) AS seat_counts
+ORDER BY id ASC;

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-bin.zip
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME