longest-consecutive-sequence solution

Author: togo26

longest-consecutive-sequence/togo26.js

@@ -0,0 +1,63 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+
+/*
+TC: O(n) -> for의 skip 부분을 while loop 분으로 채워짐
+SC: O(n) => Set 사용
+*/
+var longestConsecutive = function (nums) {
+  const numsSet = new Set(nums);
+  let seq = 0;
+
+  for (num of numsSet) {
+    if (numsSet.has(num - 1)) continue;
+
+    let next = num + 1;
+    let currentSeq = 1;
+
+    while (numsSet.has(next)) {
+      currentSeq++;
+      next++;
+    }
+
+    seq = Math.max(seq, currentSeq);
+  }
+
+  return seq;
+};
+
+/*
+memory out
+*/
+// var longestConsecutive = function(nums) {
+//     if (nums.length <= 1) return nums.length;
+
+//     const dedupeNums = new Set(nums);
+
+//     let maxValue = -Infinity;
+//     let minValue = Infinity;
+//     dedupeNums.forEach((num) => {
+//         maxValue = Math.max(maxValue, num);
+//         minValue = Math.min(minValue, num);
+//     });
+
+//     const markers = Array.from({ length: maxValue - minValue + 1 }, () => false);
+//     let maxSequence = 0;
+//     let currentSequence = 0;
+
+//     dedupeNums.forEach((num) => {
+//         markers[num - minValue] = true;
+//     });
+
+//     for (let i = 0; i < markers.length; i++) {
+//         if (markers[i]) currentSequence++;
+//         else {
+//             maxSequence = Math.max(maxSequence, currentSequence);
+//             currentSequence = 0;
+//         }
+//     }
+
+//     return Math.max(maxSequence, currentSequence);
+// };