[casentino] WEEK 01 solutions

[casentino] WEEK 01 solutions

Author: casentino

contains-duplicate/casentino.ts

@@ -0,0 +1,4 @@
+function containsDuplicate(nums: number[]): boolean {
+  const duplicateSet = new Set(nums);
+  return duplicateSet.size !== nums.length;
+}

house-robber/casentino.ts

@@ -0,0 +1,16 @@
+function rob(nums: number[]): number {
+  const memo = new Array(nums.length).fill(-1);
+
+  function dp(n: number) {
+    if (n < 0) {
+      return 0;
+    }
+    if (memo[n] !== -1) {
+      return memo[n];
+    }
+    memo[n] = Math.max(dp(n - 1), dp(n - 2) + nums[n]);
+    return memo[n];
+  }
+
+  return dp(nums.length - 1);
+}

longest-consecutive-sequence/casentino.ts

@@ -0,0 +1,20 @@
+function longestConsecutive(nums: number[]): number {
+  if (nums.length === 0) {
+    return 0;
+  }
+
+  const smallest = nums.sort((a, b) => a - b);
+  let longest = 1;
+  let sequence = 1;
+  for (let i = 1; i < smallest.length; i++) {
+    if (smallest[i] - smallest[i - 1] === 1) {
+      sequence += 1;
+    } else if (smallest[i] !== smallest[i - 1]) {
+      sequence = 1;
+    }
+    if (longest < sequence) {
+      longest = sequence;
+    }
+  }
+  return longest;
+}

top-k-frequent-elements/casentino.ts

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+function topKFrequent(nums: number[], k: number): number[] {
+  const numsMap = new Map<number, number>();
+  for (let i = 0; i < nums.length; i++) {
+    if (numsMap.has(nums[i])) {
+      numsMap.set(nums[i], (numsMap.get(nums[i]) ?? 0) + 1);
+    } else {
+      numsMap.set(nums[i], 1);
+    }
+  }
+  const sortedNums = Array.from(numsMap).sort(([_a, a], [_b, b]) => b - a);
+  const results: number[] = [];
+  for (let j = 0; j < sortedNums.length && results.length < k; j++) {
+    results.push(sortedNums[j][0]);
+  }
+  return results;
+}

two-sum/casentino.ts

@@ -0,0 +1,9 @@
+function twoSum(nums: number[], target: number): number[] | undefined {
+  for (let i = 0; i < nums.length; i++) {
+    for (let j = i + 1; j < nums.length; j++) {
+      if (nums[i] + nums[j] === target) {
+        return [i, j];
+      }
+    }
+  }
+}