<?php
//插值查找(前提是數(shù)組必須是有序數(shù)組) 事件復(fù)雜度　O(logn)
//但對(duì)于數(shù)組長(zhǎng)度比較大，關(guān)鍵字分布又是比較均勻的來說，插值查找的效率比折半查找的效率高
$i = 0; //存儲(chǔ)對(duì)比的次數(shù)
//@param 待查找數(shù)組
//@param 待搜索的數(shù)字
function insertsearch($arr,$num){
 $count = count($arr);
 $lower = 0;
 $high = $count - 1;
 global $i;
 while($lower <= $high){
  $i ++; //計(jì)數(shù)器
  if($arr[$lower] == $num){
   return $lower;
  }
  if($arr[$high] == $num){
   return $high;
  }
  // 折半查找 ： $middle = intval(($lower + $high) / 2);
  $middle = intval($lower + ($num - $arr[$lower]) / ($arr[$high] - $arr[$lower]) * ($high - $lower)); 
  if($num < $arr[$middle]){
   $high = $middle - 1;
  }else if($num > $arr[$middle]){
   $lower = $middle + 1;
  }else{
   return $middle;
  }
 }
 return -1;
}
$arr = array(0,1,16,24,35,47,59,62,73,88,99);
$pos = insertsearch($arr,62);
print($pos);
echo "<br>";
echo $i;

$arr = array(0,1,2,2000,2001,2002,2003,2004,5555,69666,99999,100000);
echo "位置：".binsearch($arr,5555);
echo "<br>";
echo "比較次數(shù)：".$i;
$i = 0; //重置比較次數(shù)
echo "<br>";
echo "位置：".insertsearch($arr,5555);
echo "<br>";
echo "比較次數(shù)：".$i;

位置：8
比較次數(shù)：2
位置：8
比較次數(shù)：9