作业帮研发笔试

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1.将数组中的0移到后面

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private static int[] func(int[] arr) {
    int length = arr.length;
    int i = 0;
    int j = 0;
    while (i < length) {
        if ((arr[i] != 0)) {
            arr[j] = arr[i];
            j++;
        }
        i++;
    }
    while (j < length) {
        arr[j] = 0;
        j++;
    }
    return arr;
}

2.求 PV，UV

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CREATE TABLE `zybang_uv_pv` (
  `url` varchar(255) DEFAULT NULL,
  `uid` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;


INSERT INTO `zybang_uv_pv` (`url`, `uid`) VALUES
('www.zybang.com', 1),
('www.zybang.com', 2),
('www.zybang.com', 3),
('www.zybang.com', 4),
('www.zybang.com', 2),
('www.zybang.com', 3),
('zhibo.zybang.com', 1),
('zhibo.zybang.com', 3),
('zhibo.zybang.com', 4),
('zhibo.zybang.com', 5);

select * from zybang_uv_pv;
+------------------+------+
| url              | uid  |
+------------------+------+
| www.zybang.com   |    1 |
| www.zybang.com   |    2 |
| www.zybang.com   |    3 |
| www.zybang.com   |    4 |
| www.zybang.com   |    2 |
| www.zybang.com   |    3 |
| zhibo.zybang.com |    1 |
| zhibo.zybang.com |    3 |
| zhibo.zybang.com |    4 |
| zhibo.zybang.com |    5 |
+------------------+------+

输出

+------------------+----+----+
| url              | uv | pv |
+------------------+----+----+
| www.zybang.com   |  4 |  6 |
| zhibo.zybang.com |  4 |  4 |
+------------------+----+----+
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select uv.url, uv.uv, pv.pv from 
((select url, count(distinct uid) as uv from zybang_uv_pv group by url) as uv) , 
((select url, count(uid) as pv from zybang_uv_pv group by url) as pv) 
where uv.url = pv.url 
order by uv.url asc;