From 1ae0cb4b893605830589580c1a5a75169e60e77f Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Sun, 4 Aug 2024 23:19:43 +0200
Subject: [PATCH] =?UTF-8?q?java:=20add=20=C2=AB128.=20Longest=20Consecutiv?=
 =?UTF-8?q?e=20Sequence=C2=BB?=
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Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 java/longest-consecutive-sequence.java | 33 ++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 java/longest-consecutive-sequence.java

diff --git a/java/longest-consecutive-sequence.java b/java/longest-consecutive-sequence.java
new file mode 100644
index 0000000..b0126f8
--- /dev/null
+++ b/java/longest-consecutive-sequence.java
@@ -0,0 +1,33 @@
+import java.util.HashMap;
+
+class Solution {
+  public int longestConsecutive(int[] nums) {
+    var uniqueNums = new HashMap<Integer, Boolean>();
+    for (var num : nums) {
+      uniqueNums.put(num, false);
+    }
+
+    // mark the possible starts
+    for (var num : nums) {
+      if (!uniqueNums.containsKey(num - 1)) {
+        uniqueNums.put(num, true);
+      }
+    }
+
+    var longest = 0;
+    for (var num : uniqueNums.entrySet()) {
+      if (!num.getValue()) {
+        continue;
+      }
+
+      var length = 1;
+      for (int x = num.getKey() + 1; uniqueNums.containsKey(x); ++x) {
+        ++length;
+      }
+
+      longest = Math.max(longest, length);
+    }
+
+    return longest;
+  }
+}