feat: longest Consecutive Sequence solution

Author: sm9171

longest-consecutive-sequence/sm9171.java

@@ -0,0 +1,20 @@
+class Solution {
+    public int longestConsecutive(int[] nums) {
+        int longest = 0;
+        Set<Integer> set = Arrays.stream(nums)
+                .boxed()
+                .collect(Collectors.toSet());
+
+        for (Integer i : set) {
+            if (set.contains(i - 1)) continue;
+            int length = 1;
+
+            while (set.contains(i + 1)) {
+                length++;
+                i++;
+            }
+            longest = Math.max(longest, length);
+        }
+        return longest;
+    }
+}