[meteorqz6] WEEK 01 Solutions (#2929)

* contains duplicate solution

* two sum solution

* longest consecutive sequence solution

Author: meteorqz6

contains-duplicate/meteorqz6.js

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+// 시간 복잡도: O(n)
+// 공간 복잡도: O(n)
+
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function (nums) {
+  const set = new Set(nums);
+  if (set.size < nums.length) return true;
+  else return false;
+};

longest-consecutive-sequence/meteorqz6.js

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+// 시간 복잡도: O(n log n)
+// 공간 복잡도: O(n)
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function (nums) {
+  let cnt = 0;
+  const set = new Set(nums);
+  const sortArray = Array.from(set).sort((a, b) => a - b);
+  const cntArray = [];
+
+  for (let i = 0; i < sortArray.length; i++) {
+    if (sortArray[i] + 1 !== sortArray[i + 1]) {
+      cntArray.push(cnt + 1);
+      cnt = 0;
+    } else {
+      cnt += 1;
+    }
+  }
+
+  if (nums.length === 0) return 0;
+  else return Math.max(...cntArray);
+};

two-sum/meteorqz6.js

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+// 시간 복잡도: O(n^2)
+// 공간 복잡도: O(1)
+
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function (nums, target) {
+  for (let i = 0; i < nums.length; i++) {
+    for (let j = i + 1; j < nums.length; j++) {
+      if (nums[i] + nums[j] === target) {
+        return [i, j];
+      }
+    }
+  }
+};