Add solution 149.

Author: javadev

src/Algorithms/0149.max-points-on-a-line/max-points-on-a-line.php

@@ -0,0 +1,98 @@
+/**
+ * Definition for a point.
+ * class Point(
+ *     public $x = 0;
+ *     public $y = 0;
+ *     function __construct(int $x = 0, int $y = 0) {
+ *         $this->x = $x;
+ *         $this->y = $y;
+ *     }
+ * )
+ */
+class Solution {
+
+    /**
+     * @param Point[] $points
+     * @return Integer
+     */
+    function maxPoints($points) {
+        $max = 0;
+        $duplicated = 0;
+        $isMaxChanged = false;
+        if ($points == null || count($points) == 0) {
+            return 0;
+        } else if (count($points) == 1) {
+            return 1;  
+        } else if (count($points) == 2) {
+            return 2;
+        } else {
+            for ($i=0;$i<count($points);$i++) {
+		//key is a string = y + "/" + x to prevent from division/float/double/BigDecimal
+		//value is amount of points on the same line -1
+            	$amount = [];
+		//j=i+1 to prevent from backwarding loop
+                for ($j=$i+1;$j<count($points);$j++) {
+                    $y = $points[$j]->y - $points[$i]->y;
+                    $x = $points[$j]->x - $points[$i]->x;
+                	
+                    if ($x == 0 && $y == 0) {
+                	$duplicated++;
+                	if ($isMaxChanged == true) {
+                	    $max++;
+                	} else if ($max < $duplicated) {
+                	    $max = $duplicated;
+                	}
+                		
+                    } else {
+                	$gcd = self::getGCD($y,$x);
+                	if ($gcd != 0) {
+                 	    $y = intval($y / $gcd);
+	              	    $x = intval($x / $gcd);
+	               	    $k = $y."/".$x;
+	                    if (array_key_exists($k, $amount)) {
+	                	$n = $amount[$k];
+	                	$amount[$k] = $n+1;
+	                	if ($max < $n+1+$duplicated) {
+	                	    $max = $n+1+$duplicated;
+	                	    $isMaxChanged = true;
+	                	}
+	                    } else {
+	                	$amount[$k] = 1;
+	                	if ($max < 1+$duplicated) {
+	                	    $max = 1+$duplicated;
+	                	    $isMaxChanged = true;
+	                	}
+	                    }
+	                }
+                    }
+                }
+
+                $duplicated = 0;
+                $isMaxChanged = false;
+                
+            }
+            return $max+1;
+        }
+    }
+    
+    //horizontal lines make x=0 & y=1
+    //vertical lines make x=1 & y=0
+    //same position points should not invoke this function whick make x=0 & y=0
+    //other points return the gcd
+    function getGCD($y, $x) {
+    	if ($x == 0) {
+    	    if ($y == 0) {
+    		return 0;//same point
+    	    } else {
+    		return $y;//horizontal lines
+    	    }
+    	} else {
+	    //normal case and the vertical lines
+	    if ($y%$x != 0) {
+	    	return self::getGCD($x,$y%$x);
+	    } else {
+	    	return $x;
+	    }
+    	}
+    }
+}