[prgmr99] WEEK 01 solutions

contains-duplicate/prgmr99.js

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

house-robber/prgmr99.js

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+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var rob = function (nums) {
+  let maxMoneyAtPrevHouse = 0;
+  let maxMoneyAtTwoHousesBack = 0;
+
+  for (let i = 0; i < nums.length; i++) {
+    let currentMax = Math.max(
+      nums[i] + maxMoneyAtTwoHousesBack,
+      maxMoneyAtPrevHouse
+    );
+
+    maxMoneyAtTwoHousesBack = maxMoneyAtPrevHouse;
+    maxMoneyAtPrevHouse = currentMax;
+  }
+
+  return maxMoneyAtPrevHouse;
+};

longest-consecutive-sequence/prgmr99.js

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+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var longestConsecutive = function (nums) {
+  let result = 1;
+  let maxLength = 1;
+
+  if (nums.length === 0) return 0;
+
+  const sortedNums = nums.sort((a, b) => a - b);
+
+  for (let i = 1; i < sortedNums.length; i++) {
+    const prevNum = sortedNums[i - 1];
+    const currentNum = sortedNums[i];
+
+    const diff = currentNum - prevNum;
+
+    if (diff === 1) {
+      result += 1;
+
+      if (maxLength < result) {
+        maxLength = result;
+      }
+    } else if (diff === 0) {
+      continue;
+    } else {
+      result = 1;
+    }
+  }
+
+  return maxLength;
+};

top-k-frequent-elements/prgmr99.js

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

two-sum/prgmr99.js

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