feat: solve longest-consecutive-sequence

Author: GangBean

longest-consecutive-sequence/GangBean.java

@@ -0,0 +1,23 @@
+import java.util.*;
+import java.util.stream.Collectors;
+
+class Solution {
+    public int longestConsecutive(int[] nums) {
+        Set<Integer> set = Arrays.stream(nums).boxed().collect(Collectors.toSet());
+
+        int maxLength = 0;
+        for (int num: nums) {
+            // 각 숫자에 대해 최초 값이 가능하면, 즉 num-1이 존재하지 않으면 최대 length 구하기
+            if (set.contains(num - 1)) continue;
+            int length = 1;
+            int start = num;
+            while (set.contains(start + 1)) {
+                length++;
+                start++;
+            }
+            maxLength = Math.max(length, maxLength);
+        }
+
+        return maxLength;
+    }
+}