[TotschKa] Week 1

contains-duplicate/Totschka.ts

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+// https://leetcode.com/problems/contains-duplicate/
+function containsDuplicate(nums: number[]): boolean {
+  const counter = {};
+  for (const n of nums) {
+    if (!counter[n]) {
+      counter[n] = 1;
+    } else {
+      return true;
+    }
+  }
+  return false;
+}

house-robber/Totschka.ts

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+// https://leetcode.com/problems/house-robber/
+let dp;
+function rob(nums: number[]): number {
+  dp = Array.from({ length: nums.length + 1 }, () => -1);
+  return doRobbery(nums, nums.length - 1);
+}
+
+function doRobbery(nums: number[], i: number) {
+  if (i < 0) {
+    return 0;
+  }
+  if (dp[i] >= 0) {
+    return dp[i];
+  }
+  const money = Math.max(doRobbery(nums, i - 2) + nums[i], doRobbery(nums, i - 1));
+  dp[i] = money;
+  return money;
+}

longest-consecutive-sequence/Totschka.ts

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+// https://leetcode.com/problems/longest-consecutive-sequence/
+function longestConsecutive(nums: number[]): number {
+  if (nums.length === 0) {
+    return 0;
+  }
+  nums = [...new Set(nums)].sort((a, b) => a - b);
+  let ans = 0;
+  let left = 0, right = 1;
+  for (let i = 0; i < nums.length; i++) {
+    if (nums[i] + 1 === nums[i + 1]) {
+      ans = Math.max(ans, right - left);
+    } else {
+      left = right;
+    }
+    right++;
+  }
+  return ans + 1;
+}

top-k-frequent-elements/Totschka.ts

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+// https://leetcode.com/problems/top-k-frequent-elements/
+function topKFrequent(nums: number[], k: number): number[] {
+  const counter = new Map<number, number>();
+  for (const n of nums) {
+    counter.set(n, (counter.get(n) ?? 0) + 1);
+  }
+  return [...counter.keys()]
+    .sort((a, b) => counter.get(b)! - counter.get(a)!)
+    .slice(0, k);
+}

valid-palindrome/Totschka.ts

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+// https://leetcode.com/problems/valid-palindrome/description/
+function isPalindrome(s: string): boolean {
+  s = s.replace(/[^a-zA-Z0-9]/g, '').toLowerCase();
+  for (let i = 0; i < s.length / 2; i++) {
+    if (s[i] !== s[s.length - 1 - i]) {
+      return false;
+    }
+  }
+  return true;
+}