Question

给出一个列表，列出他们的出生日期和结束年份（都在1900年至2017年之间），找出活着的人最多的年份。

<?php
class Person {
    function __construct($birth, $death) {
    $this->birthYear = $birth;
    $this->deathYear = $death;
  }
};

$people = [
  new Person(1925, 1972),//47
  new Person(1901, 1960),//59
  new Person(1942, 1999),//57
  new Person(1960, 2010),//50
  new Person(1931, 2017),//86
  new Person(1961, 1995),//34
  new Person(1919, 1982),//63
];
$birth = array_column($people,"birthYear");
$death = array_column($people,"deathYear");
$START_YEAR = 1900;
$END_YEAR = 2017+1;
$people_alive = [];
$people = json_decode(json_encode($people),true);

foreach($people as $k=>$v){
    $a = $v['birthYear'] - $START_YEAR;
    $b = $v['deathYear'] - $START_YEAR +1;
    $people_alive[]= $b-$a +1;
}
print_r($people_alive);

我试图将解决方案从python转换为PHP，但这不是我想要的。 python解决方案

Array
(
    [0] => 49
    [1] => 61
    [2] => 59
    [3] => 52
    [4] => 88
    [5] => 36
    [6] => 65
)

我想要一年中大多数人还活着的一年。我对如何创建此逻辑感到困惑。

Answer 1

最简单的解决方案是遍历所有年份，并计算给定年份有多少人还活着。然后，找到人数最多的年份-那将是活着的人数最多的年份。请记住，此解决方案不是最佳解决方案，并且具有复杂性O(n)：

<?php
class Person {
    public function __construct($birth, $death) {
        $this->birthYear = $birth;
        $this->deathYear = $death;
    }
};

$people = [
    new Person(1925, 1972),//47
    new Person(1901, 1960),//59
    new Person(1942, 1999),//57
    new Person(1960, 2010),//50
    new Person(1931, 2017),//86
    new Person(1961, 1995),//34
    new Person(1919, 1982),//63
];

$start = 1900;
$end = 2017;

// create list of years in given time frame
$years = array_fill($start, $end - $start + 1, 0);

// iterate through all the people
foreach ($people as $person) {
    for ($i = $person->birthYear; $i <= $person->deathYear; ++$i) {
        $years[$i] += 1;
    }
}

// the maximum number of people alive in one year
$max_count = max($years);
// the year with the most number of people alive
$max_year = array_search($max_count, $years);

查找在PHP中存活人数最多的年份

1 个答案: