[yhkee0404] WEEK 01 solutions

contains-duplicate/yhkee0404.kt

@@ -0,0 +1,6 @@
+class Solution {
+    fun containsDuplicate(nums: IntArray): Boolean {
+        return nums.toSet()
+                .size != nums.size
+    }
+}

house-robber/yhkee0404.rs

@@ -0,0 +1,11 @@
+impl Solution {
+    pub fn rob(nums: Vec<i32>) -> i32 {
+        let mut dp = vec![0; nums.len() + 1];
+        dp[1] = nums[0];
+        for i in 2..dp.len() {
+            dp[i] = dp[i - 1].max(dp[i - 2] + nums[i - 1]);
+        }
+        return *dp.last()
+                .unwrap_or(&0)
+    }
+}

longest-consecutive-sequence/yhkee0404.go

@@ -0,0 +1,22 @@
+func longestConsecutive(nums []int) int {
+    ans := 0
+    sort.Ints(nums)
+    i := 0
+    for i != len(nums) {
+        j := i + 1
+        k := 0
+        for j != len(nums) {
+            diff := nums[j] - nums[j - 1]
+            if diff > 1 {
+                break
+            }
+            j++
+            if diff == 0 {
+                k++
+            }
+        }
+        ans = max(ans, j - i - k)
+        i = j
+    }
+    return ans
+}

top-k-frequent-elements/yhkee0404.scala

@@ -0,0 +1,11 @@
+object Solution {
+    def topKFrequent(nums: Array[Int], k: Int): Array[Int] = {
+        return nums.groupBy(identity)
+                .view.mapValues(_.size)
+                .toSeq
+                .sortBy(- _._2)
+                .take(k)
+                .map(_._1)
+                .toArray
+    }
+}

two-sum/yhkee0404.go

@@ -0,0 +1,11 @@
+func twoSum(nums []int, target int) []int {
+    indices := make(map[int]int)
+    for i, num := range nums {
+        j, ok := indices[target - num]
+        if ok {
+            return []int{j, i}
+        }
+        indices[num] = i
+    }
+    return []int{}
+}