How many numbers is less than the current number

Address: https://leetcode-cn.com/problems/how-many-numbers-are-smaller-than-the-current-number/

<?php

/**
To give you an array nums, all figures for the number of each element nums [i], you count the array smaller than it therein.

In other words, for each nums [i] You must calculate the effective number of j, where j satisfies j! = I and nums [j] <nums [i].

The answer is returned in an array.

 

Example 1:

Input: nums = [8,1,2,2,3]
Output: [4,0,1,1,3]
Explanation:
For nums [0] = 8, there are four smaller than its numbers: (1,2,2, and 3).
For nums [1] = 1 is smaller than its number does not exist.
There is a smaller number than it is for nums [2] = 2: (1).
For nums [3] = 2 there is a smaller number than it: (1).
For nums [4] = 3 it is smaller than the presence of three figures: (1 and 2).
Example 2:

Input: nums = [6,5,4,8]
Output: [2,1,0,3]
Example 3:

Input: nums = [7,7,7,7]
Output: [0,0,0,0]
 

prompt:

2 <= nums.length <= 500
0 <= nums[i] <= 100
 */
class Solution {
    /**
     1. Create a new array, for him to sort into [8,3,2,2,1]
     2. interchangeable key-value pair [ "8" => 0, "3" => 1, "2" => 3, "1" => 4]
     3. Obtain the number less than the current value, because it is over the discharge sequence, so the subscript can represent numbers greater than he has several
     * ["8"=>5-1-0,"3"=>5-1-1,"2"=>5-1-3,"1"=>5-1-4]
     *  ["8"=>4,"3"=>3,"2"=>1,"1"=>0]
     4. convenient source array, filling values ​​[4,0,1,1,3]
     */
    function smallerNumbersThanCurrent1($nums) {
        $tmp_arr = $nums;
        rsort($tmp_arr);
        $tmp_arr = array_flip($tmp_arr);
        $length = count($nums);

        foreach ($tmp_arr as $key => $value) {
            $tmp_arr[$key] = $length - 1 -$tmp_arr[$key];
        }
        $arr = [];

        foreach ($nums as $value) {
            $arr[] = $tmp_arr[$value];
        }
        return $arr;
    }
    /**
    1 Create an array, for him to sort into [1,2,2,3,8]
    2 convenient source array, nest convenient new array, a new array index is equal to the number of in front of him as much as his array
     */
    function smallerNumbersThanCurrent($nums) {
        $old_arr = $nums;
        $new_arr =[];
       sort($old_arr);
       for($i =0;$i<count($nums);$i++){
           foreach ($old_arr as $index=> $num){
               if ($num == $nums[$i]) {
                   array_push($new_arr,$index);
                   break;
                   }
           }
       }
        return $new_arr;
    }
}
$arr = [8,1,2,2,3];
$arr1 = [7,7,7,7];
$solution = new Solution();
var_dump($solution->smallerNumbersThanCurrent($arr));