How to count the number of times a number appears in a sorted array in PHP (code)

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Count the number of times a number appears in the sorted array.
1. Ordered array search, use binary method
2. Binary method to find the position of the first occurrence, binary method to find the position of the last occurrence, end - start 1

left=getLeft(data,k)
right=getRight(data,k)
retun right-left+1
getLeft data,k
    left=0
    right=arr.length-1
    mid=left+(right-left)/2
    while  left<=right
        if arr[mid]<k    //关键
            left=mid+1
        else
            right=mid-1
        mid=left+(right-left)/2
    return left
getRight data,k
    left=0
    right=arr.length-1
    mid=left+(right-left)/2
    while  left<=right
        if arr[mid]<=k   //关键
            left=mid+1
        else
            right=mid-1
        mid=left+(right-left)/2
    return right

<?php
function GetNumberOfK($data, $k) 
{
        $left=getLeft($data,$k);
        $right=getRight($data,$k);
        return $right-$left+1;
}
function getLeft($arr,$k){
        $left=0;
        $right=count($arr)-1;
        $mid=intval($left+($right-$left)/2);
        while($left<=$right){
                if($arr[$mid]>=$k){//关键
                        $right=$mid-1;
                }else{
                        $left=$mid+1;
                }   
                $mid=intval($left+($right-$left)/2);
        }   
        return $left;
}
function getRight($arr,$k){
        $left=0;
        $right=count($arr)-1;
        $mid=intval($left+($right-$left)/2);
        while($left<=$right){
                if($arr[$mid]<=$k){//关键
                        $left=$mid+1;
                }else{
                        $right=$mid-1;
                }   
                $mid=intval($left+($right-$left)/2);
        }   
        return $right;
}
$arr=array(1,2,3,4,4,4,5);
$m=GetNumberOfK($arr,4);
var_dump($m);

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