[hsskey] WEEK 1 solutions

contains-duplicate/hsskey.js

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+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function(nums) {
+    return nums.length !== new Set([...nums]).size
+};

house-robber/hsskey.js

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+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var rob = function(nums) {
+    if (nums.length === 0) return 0;
+    if (nums.length === 1) return nums[0];
+
+    const dp = new Array(nums.length);
+
+    dp[0] = nums[0];
+    dp[1] = Math.max(nums[0], nums[1]);
+
+    for (let i = 2; i < nums.length; i++) {
+        dp[i] = Math.max(nums[i] + dp[i - 2], dp[i - 1]);
+    }
+
+    return dp[nums.length - 1];
+};

longest-consecutive-sequence/hsskey.js

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+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function(nums) {
+    const numSet = new Set(nums);
+    let maxLength = 0;
+
+    for (const num of nums) {
+        if (!numSet.has(num - 1)) {
+            let currentNum = num;
+            let currentLength = 1;
+
+            while (numSet.has(currentNum + 1)) {
+                currentNum++;
+                currentLength++;
+            }
+            maxLength = Math.max(maxLength, currentLength);
+        }
+    }
+
+    return maxLength;
+};

top-k-frequent-elements/hsskey.js

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+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number[]}
+ */
+var topKFrequent = function(nums, k) {
+    const map = new Map()
+
+    for(let i = 0; i < nums.length; i++) {
+        if(map.has(nums[i])) {
+            const prevVal = map.get(nums[i])
+            map.set(nums[i], prevVal + 1)
+        } else {
+            map.set(nums[i], 1)
+        }
+    }
+
+    const result = [...map.entries()].sort((a, b) => b[1] - a[1]).slice(0, k).map((item) => {
+        return item[0]
+    })
+    return result
+};

two-sum/hsskey.js

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