exercise/id169

src/main/kotlin/exercise100/easy/id169/Description169.md

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+[//]: # (Copyright [2023] [Anton Kotler kotler.developer@gmail.com] License MIT)
+
+# Majority Element
+
+![Difficulty](https://img.shields.io/badge/Difficulty-Easy-61904f)
+
+Given an array `nums` of size `n`, return the majority element.  
+The majority element is the element that appears more than `|n / 2|` times.  
+You may assume that the majority element always exists in the array.
+
+Example 1:
+
+```
+Input: nums = [3,2,3]
+Output: 3
+```
+
+Example 2:
+
+```
+Input: nums = [2,2,1,1,1,2,2]
+Output: 2
+```
+
+Constraints:
+
+- `n == nums.length`
+- `1 <= n <= 5 * 10^4`
+- `-10^9 <= nums[i] <= 10^9`
+
+Follow-up: Could you solve the problem in linear time and in `O(1)` space?
+
+| ID  | Description      |           Solution           |                                        Test                                         | Difficulty |
+|:---:|:-----------------|:----------------------------:|:-----------------------------------------------------------------------------------:|:----------:|
+| 169 | Majority Element | [solution](./Solution169.kt) | [test](../../../../../../src/test/kotlin/exercise100/easy/id169/Solution169Test.kt) |    Easy    |
+
+:top: [Back to all topics](https://github.com/kotler-dev/kotlin-leetcode)

src/main/kotlin/exercise100/easy/id169/Solution169.kt

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+package exercise100.easy.id169
+
+class Solution169 {
+    fun majorityElement(nums: IntArray): Int {
+        val hm = HashMap<Int, Int>()
+        nums.forEach {
+            val n = hm[it]
+            if (n == null) hm[it] = 0
+            if (n != null) hm[it] = n + 1
+        }
+        return hm.maxBy { n -> n.value }.key
+    }
+
+    /*
+
+
+
+    */
+}

src/test/kotlin/exercise100/easy/id169/Solution169Test.kt

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+package exercise100.easy.id169
+
+import io.kotest.assertions.print.print
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.datatest.WithDataTestName
+import io.kotest.datatest.withData
+import io.kotest.matchers.shouldBe
+
+data class TestCase(
+    val prices: IntArray,
+    val expected: Int,
+) : WithDataTestName {
+    override fun dataTestName(): String = expected.print().value
+}
+
+class Solution169Test : FunSpec({
+    context("shouldBe") {
+        withData(
+            nameFn = { "Input: ${it.prices.print().value}, Expected: ${it.expected.print().value}" },
+            TestCase(prices = intArrayOf(3, 2, 3), expected = 3),
+            TestCase(prices = intArrayOf(2, 2, 1, 1, 1, 2, 2), expected = 2),
+        ) { (prices, expected) ->
+            Solution169().majorityElement(prices) shouldBe expected
+        }
+    }
+})