Add solution 164.

Author: javadev

src/Algorithms/0164.maximum-gap/maximum-gap.php

@@ -0,0 +1,67 @@
+class Bucket {
+    var $leftClose;
+    var $rightOpen;
+    var $usedFlag;
+
+    function __construct() {
+        $this->leftClose = 0;
+        $this->rightOpen = 0;
+        $this->usedFlag = false;
+    }
+}
+
+class Solution {
+
+    /**
+     * @param Integer[] $nums
+     * @return Integer
+     */
+    function maximumGap($nums) {
+        if ($nums==null || count($nums)<2) {
+            return 0;
+        }
+
+        // find the maximum value and the minimum value in array
+        $max = $nums[0];
+        $min = $nums[0];
+        foreach ($nums as $num) {
+            $max = $max<$num ? $num : $max;
+            $min = $min>$num ? $num : $min;
+        }
+
+        // the size of bucket must > 1
+        $bucketSize = intval(max(1, ($max - $min) / (count($nums) - 1)));
+        $bucketNum = intval(($max-$min) / $bucketSize + 1);
+
+        $buckets = array_fill(0, $bucketNum, null);
+
+            $buckets[$i] = new Bucket();
+        }
+
+        // locating correct bucket
+        foreach ($nums as $num) {
+            $bucketIndex = intval(($num - $min) / $bucketSize);
+
+            if ($buckets[$bucketIndex]->usedFlag == false) {
+                $buckets[$bucketIndex]->leftClose = $num;
+                $buckets[$bucketIndex]->rightOpen = $num;
+                $buckets[$bucketIndex]->usedFlag = true;
+            } else {
+                $buckets[$bucketIndex]->leftClose = min($num, $buckets[$bucketIndex]->leftClose);
+                $buckets[$bucketIndex]->rightOpen = max($num, $buckets[$bucketIndex]->rightOpen);
+            }
+        }
+
+        $maxGap = 0;
+        $preRightOpen = $buckets[0]->rightOpen;
+
+            if ($buckets[$i]->usedFlag == false) {
+                continue;
+            }
+            $maxGap = max($maxGap, $buckets[$i]->leftClose-$preRightOpen);
+            $preRightOpen = $buckets[$i]->rightOpen;
+        }
+
+        return $maxGap;
+    }
+}