算法要求:给定一个矩阵matrix,绕着圈圈的方式输入打印他,要求空间复杂度为O(1)
例如
2 3 13 24 35
16 27 18 29 10
11 12 43 34 45
16 11 17 19 20
打印结果为:2 3 13 24 35 10 45 20 19 17 11 16 11 16 27 18 29 34 43 12
//算法思路
核心1:左上XY座标跟右上XY座标,从外圈开始打印,一层一层向内打印
核心2:用数组代替矩阵进行表示,特别注意XY座标之间的关系
算法代码(PHP版)
class CircleMartixPrint
{
public static function circleMartix($martix)
{
//左上X座标
$leftX = 0;
//左上Y座标
$leftY = 0;
//右下X座标
$rightX = count($martix) – 1;
//右下Y座标
$rightY = count($martix[0]) – 1;
while ($leftX <= $rightX && $leftY <= $rightY) {
self::printEdge($martix, $leftX++, $leftY++, $rightX–, $rightY–);
}
}
private static function printEdge($martix, $leftX, $leftY, $rightX, $rightY)
{
//只有一行的情况
if ($leftX == $rightX) {
for ($start = $leftY; $start <= $rightY; $start++) {
echo $martix[$leftX][$start] . ”;
}
} elseif ($leftY == $rightY) {
//只有一列的情况
for ($start = $leftX; $start <= $rightX; $start++) {
echo $martix[$start][$leftY] . ”;
}
} else {
//正常矩形
$nowX = $leftX;
$nowY = $leftY;
//打印top
while ($nowY < $rightY) {
echo $martix[$nowX][$nowY] . ‘ ‘;
$nowY++;
}
//打印right
while ($nowX < $rightX) {
echo $martix[$nowX][$nowY] . ‘ ‘;
$nowX++;
}
//打印bottom
while ($nowY > $leftY) {
echo $martix[$nowX][$nowY] . ‘ ‘;
$nowY–;
}
//打印left
while ($nowX > $leftX) {
echo $martix[$nowX][$nowY] . ‘ ‘;
$nowX–;
}
}
}
}
$matrix = [
[2, 3, 13, 24, 35],
[16, 27, 18, 29, 10],
[11, 12, 43, 34, 45],
[16, 11, 17, 19, 20]
];
CircleMartixPrint::circleMartix($matrix);