php经典算法集锦

for ($i = 1; ; $i++)
{
  if ($i%5 == 1) {
    //第一个人取五分之一，还剩$t
    $t = $i - round($i/5) - 1;
    if($t % 5 == 1)
    {
      //第二个人取五分之一，还剩$r
      $r = $t - round($t/5) - 1;
      if($r % 5 == 1)
      {
        //第三个人取五分之一，还剩$s
        $s = $r - round($r/5) - 1;
        if($s % 5 == 1)
        {
          //第四个人取五分之一，还剩$x
          $x = $s - round($s/5) - 1;
          if($x % 5 == 1)
          {
            //第五个人取五分之一，还剩$y
            $y = $x - round($x/5) - 1;
            if ($y % 5 == 1) {
              echo $i;
              break;
            }
          }
        }
      }
    }
  }
}

function king($n, $m){
  $monkeys = range(1, $n);
  $i=0;
  $k=$n;
  while (count($monkeys)>1) {
    if(($i+1)%$m==0) {
      unset($monkeys[$i]);
    } else {
      array_push($monkeys,$monkeys[$i]);
      unset($monkeys[$i]);
    }
    $i++;
  }
  return current($monkeys);
}
$a = king(5, 2);
var_dump($a);

function hanoi($n,$x,$y,$z){
  if($n==1){
    echo 'move disk 1 from '.$x.' to '.$z."\n";
  }else{
    hanoi($n-1,$x,$z,$y);
    echo 'move disk '.$n.' from '.$x.' to '.$z."\n";
    hanoi($n-1,$y,$x,$z);
  }   
}
hanoi(3,'A','B','C');

//对数组冒泡排序
function bubble_sort($array){
  $count = count($array);
  if ($count <= 0) 
    return false;
    for($i=0; $i<$count; $i++){
      for($j=$count-1; $j>$i; $j–){
      if ($array[$j] < $array[$j-1]){
        $tmp = $array[$j];
        $array[$j] = $array[$j-1];
        $array[$j-1] = $tmp;
    }
  }
}
return $array;
}
function quick_sort($array) {
  if (count($array) <= 1) return $array;
  $key = $array[0];
  $left_arr = array();
  $right_arr = array();
  for ($i=1; $i<count($array); $i++){
  if ($array[$i] <= $key)
    $left_arr[] = $array[$i];
  else
    $right_arr[] = $array[$i];
  }
  $left_arr = quick_sort($left_arr);
  $right_arr = quick_sort($right_arr);
  return array_merge($left_arr, array($key), $right_arr);
}

//使用二分查找数组中某个元素
function bin_sch($array, $low, $high, $k){
  if ($low <= $high){
    $mid = intval(($low+$high)/2);
    if ($array[$mid] == $k){
      return $mid;
    }elseif ($k < $array[$mid]){
    return bin_sch($array, $low, $mid-1, $k);
  }else{
    return bin_sch($array, $mid+1, $high, $k);
  }
  }
  return -1;
}

function array_sort($arr, $keys, $order=0) {
  if (!is_array($arr)) {
    return false;
  }
  $keysvalue = array();
  foreach($arr as $key => $val) {
    $keysvalue[$key] = $val[$keys];
  }
  if($order == 0){
    asort($keysvalue);
  }else {
    arsort($keysvalue);
  }
  reset($keysvalue);
  foreach($keysvalue as $key => $vals) {
    $keysort[$key] = $key;
  }
  $new_array = array();
  foreach($keysort as $key => $val) {
    $new_array[$key] = $arr[$val];
  }
  return $new_array;
}