spoj16935 Straight Line Spiral Pattern (Act 3)

题目：http://www.spoj.com/problems/SPTTRN3/

题意：输出螺旋的图案，图案规则是先顺时针画一圈星号，但是首尾不能相连，然后在第二层中隔两点，接着是逆时针画圈

具体代码如下：

<?php$debug = false;$file = STDIN;if ($debug){$file = fopen("./spoj.txt", "r");}$t = trim(fgets($file));while ($t--){$line = trim(fgets($file));$n = intval($line);solve($n);if (0 != $t) echo PHP_EOL; }if ($debug) fclose($file);function solve($n){$matrix = array();$tmp = array();$tmp = array_pad($tmp, $n, '.');$matrix = array_pad($matrix, $n, $tmp);$clockdx = array(0, 1, 0, -1);$clockdy = array(1, 0, -1, 0);$arr[] = array($clockdx, $clockdy);$anticlockdx = array(1, 0, -1, 0);$anticlockdy = array(0, 1, 0, -1);$arr[] = array($anticlockdx, $anticlockdy);$cur = 0;$curdir = 0;$x = 0; $y = 0;$loop = (int)($n / 4);$remain = $n % 4;for ($i = 0; $i < $loop; $i++){$curx = $x; $cury = $y;while (true){$matrix[$curx][$cury] = '*';$newx = $curx + $arr[$cur][0][$curdir]; $newy = $cury + $arr[$cur][1][$curdir];//echo 'curx:', $curx, ' cury:', $cury, ' newx:', $newx, ' newy:', $newy,  PHP_EOL;if ($newx == $x && $newy == $y){$matrix[$curx][$cury] = '.';$curx -= $arr[$cur][0][$curdir];$cury -= $arr[$cur][1][$curdir];break;}if ($newx < 0 + $i * 2 || $newx >= $n - $i * 2 || $newy < 0 + $i * 2 || $newy >= $n - $i * 2){$curdir = ($curdir + 1) % 4;continue;}$curx = $newx; $cury = $newy;}if ($loop - 1 != $i){$curdir = ($curdir + 1) % 4;$curx = $curx + $arr[$cur][0][$curdir]; $cury = $cury + $arr[$cur][1][$curdir];$matrix[$curx][$cury] = '*';$x = $curx + $arr[$cur][0][$curdir]; $y = $cury + $arr[$cur][1][$curdir];$cur = ($cur + 1) % 2;}}//echo 'remain:', $remain, PHP_EOL;if (0 !== $remain){$curdir = ($curdir + 1) % 4;$curx = $curx + $arr[$cur][0][$curdir]; $cury = $cury + $arr[$cur][1][$curdir];$matrix[$curx][$cury] = '*';$x = $curx + $arr[$cur][0][$curdir]; $y = $cury + $arr[$cur][1][$curdir];$cur = ($cur + 1) % 2;$curx = $x; $cury = $y;while ($remain--){while (true){$matrix[$curx][$cury] = '*';$newx = $curx + $arr[$cur][0][$curdir]; $newy = $cury + $arr[$cur][1][$curdir];//echo 'curx:', $curx, ' cury:', $cury, ' newx:', $newx, ' newy:', $newy,  PHP_EOL;if ($newx < 0 + $i * 2 || $newx >= $n - $i * 2 || $newy < 0 + $i * 2 || $newy >= $n - $i * 2){$curdir = ($curdir + 1) % 4;break;}$curx = $newx; $cury = $newy;}}}//var_dump($matrix);output($matrix);}function output($matrix){$ans = '';$size = count($matrix);for ($i = 0; $i < $size; $i++){for ($j = 0; $j < $size; $j++){$ans .= $matrix[$i][$j];}$ans .= PHP_EOL;}echo $ans;}?>