Merge pull request #2389 from DaleStudy/yihyun-kim1

[yihyun-kim1] WEEK 01 solutions

Author: yihyun-kim1

contains-duplicate/yihyun-kim1.js

@@ -0,0 +1,7 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+
+// Set은 중복을 자동으로 제거하므로 Set의 크기가 원래 배열 길이보다 작으면 중복이 존재한다는 것
+const containsDuplicate = (nums) => new Set(nums).size !== nums.length;

top-k-frequent-elements/yihyun-kim1.js

@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+const topKFrequent = (nums, k) => {
+  const map = new Map();
+
+  for (let num of nums) {
+    map.set(num, (map.get(num) || 0) + 1);
+  }
+
+  return [...map.entries()]
+    .sort((a, b) => b[1] - a[1])
+    .slice(0, k)
+    .map((entry) => entry[0]);
+};

two-sum/yihyun-kim1.js

@@ -0,0 +1,19 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+
+const twoSum = (nums, target) => {
+  const map = new Map();
+
+  for (let i = 0; i < nums.length; i++) {
+    const complement = target - nums[i];
+
+    if (map.has(complement)) {
+      return [map.get(complement), i];
+    }
+
+    map.set(nums[i], i);
+  }
+};