solve: longest consecutive sequence

Author: tolluset

longest-consecutive-sequence/tolluset.ts

@@ -0,0 +1,62 @@
+/*
+ * TC: O(n)
+ * SC: O(n)
+ * */
+function longestConsecutive(nums: number[]): number {
+  const consecutives = [...new Set(nums.sort((a, b) => b - a))];
+  const n = consecutives.length;
+
+  if (n === 0) {
+    return 0;
+  }
+
+  if (n === 1) {
+    return 1;
+  }
+
+  const bucket = [...Array(n)].map((): Set<number> => new Set());
+
+  let cursor = 0;
+
+  for (let i = 0; i < n; i++) {
+    const current = consecutives[i];
+    const left = consecutives[i - 1];
+    const right = consecutives[i + 1];
+
+    const isLeft = left !== undefined && left - current === 1;
+    const isRight = right !== undefined && current - right === 1;
+
+    const isConsecutive = isLeft || isRight;
+
+    if (isConsecutive) {
+      bucket[cursor].add(current);
+
+      if (isLeft && !isRight) {
+        cursor++;
+      }
+    } else {
+      cursor++;
+
+      continue;
+    }
+  }
+
+  const total = bucket.reduce(
+    (acc, cur) => (acc > cur.size ? acc : cur.size),
+    0,
+  );
+
+  return total === 0 ? 1 : total;
+}
+
+const t1 = longestConsecutive([100, 4, 200, 1, 3, 2]);
+console.info("🚀 : tolluset.ts:5: t1=", t1); // 4
+
+const t2 = longestConsecutive([0, 3, 7, 2, 5, 8, 4, 6, 0, 1]);
+console.info("🚀 : tolluset.ts:8: t2=", t2); // 9
+
+const t3 = longestConsecutive([9, 1, 4, 7, 3, -1, 0, 5, 8, -1, 6]);
+console.info("🚀 : tolluset.ts:40: t3=", t3); // 7
+
+const t4 = longestConsecutive([-6, -1, -1, 9, -8, -6, -6, 4, 4, -3, -8, -1]);
+console.info("🚀 : tolluset.ts:59: t4=", t4); //1