PHP数组特定元素查找的算法效率比较

function linearSearch($arr, $target) {
  for ($i = 0; $i < count($arr); $i++) {
    if ($arr[$i] === $target) {
      return $i;
    }
  }

  return -1;
}

function binarySearch($arr, $target) {
  $left = 0;
  $right = count($arr) - 1;

  while ($left <= $right) {
    $mid = floor(($left + $right) / 2);

    if ($arr[$mid] === $target) {
      return $mid;
    } else if ($arr[$mid] < $target) {
      $left = $mid + 1;
    } else {
      $right = $mid - 1;
    }
  }

  return -1;
}

function hashTableSearch($arr, $target) {
  $lookupTable = [];

  for ($i = 0; $i < count($arr); $i++) {
    $lookupTable[$arr[$i]] = true;
  }

  if (isset($lookupTable[$target])) {
    return true;
  } else {
    return false;
  }
}