[dongzoolee] WEEK 1 Solutions

contains-duplicate/dongzoolee.ts

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+function containsDuplicate(nums: number[]): boolean {
+  const sets = new Set<number>(nums);
+  return sets.size < nums.length;
+}

longest-consecutive-sequence/dongzoolee.ts

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+function longestConsecutive(nums: number[]): number {
+  const st = new Set(nums);
+
+  let mx = 0;
+  for (const n of st) {
+    if (st.has(n - 1)) continue;
+
+    let len = 1;
+    while (st.has(n + len)) {
+      len++;
+    }
+
+    mx = Math.max(mx, len);
+  }
+
+  return mx;
+}

top-k-frequent-elements/dongzoolee.ts

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+function topKFrequent(nums: number[], k: number): number[] {
+  const mp: { [k: number]: number } = {};
+  nums.forEach((n) => (typeof mp[n] === "number" ? mp[n]++ : (mp[n] = 1)));
+
+  const unq_nums = [...new Set(nums)];
+  unq_nums.sort((a, b) => {
+    if (mp[a] === mp[b]) {
+      return 0;
+    }
+
+    return mp[a] < mp[b] ? 1 : -1;
+  });
+
+  return unq_nums.slice(0, k);
+}

two-sum/dongzoolee.ts

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+function twoSum(nums: number[], target: number): number[] {
+  const sz = nums.length;
+  let l = 0,
+    r = 1,
+    sm = nums[0] + nums[1];
+
+  while (l <= sz - 2 && r <= sz - 1) {
+    sm = nums[l] + nums[r];
+
+    if (sm === target) {
+      return [l, r];
+    }
+
+    if (l === r - 1) {
+      (r++, (l = 0));
+    } else {
+      l++;
+    }
+  }
+}