Merge pull request #504 from jdalma/main

[정현준] 8주차 제출

Author: jdalma

clone-graph/jdalma.kt

@@ -0,0 +1,94 @@
+package leetcode_study
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import java.lang.RuntimeException
+import java.util.ArrayDeque
+import java.util.Queue
+
+class `clone-graph` {
+
+    data class Node(var `val`: Int) {
+        var neighbors: ArrayList<Node?> = ArrayList()
+    }
+
+    fun cloneGraph(node: Node?): Node? {
+        if (node == null) return null
+
+        return usingBFS(node)
+    }
+
+    /**
+     * TC: O(n), SC: O(n)
+     */
+    private fun usingDFS(node: Node): Node {
+
+        fun dfs(node: Node, nodes: MutableMap<Int, Node>): Node {
+            nodes[node.`val`]?.let {
+                return it
+            }
+            val copy = Node(node.`val`)
+            nodes[node.`val`] = copy
+
+            for (near in node.neighbors.filterNotNull()) {
+                copy.neighbors.add(dfs(near, nodes))
+            }
+
+            return copy
+        }
+        return dfs(node, mutableMapOf())
+    }
+
+    /**
+     * TC: O(n), SC: O(n)
+     */
+    private fun usingBFS(node: Node): Node {
+        val nodes = mutableMapOf<Int, Node>().apply {
+            this[node.`val`] = Node(node.`val`)
+        }
+        val queue: Queue<Node> = ArrayDeque<Node>().apply {
+            this.offer(node)
+        }
+
+        while (queue.isNotEmpty()) {
+            val now = queue.poll()
+            val copy = nodes[now.`val`] ?: throw RuntimeException()
+            for (near in now.neighbors.filterNotNull()) {
+                if (!nodes.containsKey(near.`val`)) {
+                    nodes[near.`val`] = Node(near.`val`)
+                    queue.add(near)
+                }
+                copy.neighbors.add(nodes[near.`val`])
+            }
+        }
+        return nodes[node.`val`] ?: Node(node.`val`)
+    }
+
+    private fun fixture(): Node {
+        val one = Node(1)
+        val two = Node(2)
+        val three = Node(3)
+        val four = Node(4)
+
+        one.neighbors.add(two)
+        one.neighbors.add(four)
+        two.neighbors.add(one)
+        two.neighbors.add(three)
+        three.neighbors.add(two)
+        three.neighbors.add(four)
+        four.neighbors.add(one)
+        four.neighbors.add(three)
+
+        return one
+    }
+
+    @Test
+    fun `입력받은 노드의 깊은 복사본을 반환한다`() {
+        val actualNode = fixture()
+        val expectNode = cloneGraph(actualNode)
+        actualNode shouldBe expectNode
+
+        actualNode.`val` = 9999
+        expectNode!!.`val` shouldBe 1
+    }
+}

longest-common-subsequence/jdalma.kt

@@ -0,0 +1,65 @@
+package leetcode_study
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import kotlin.math.max
+
+class `longest-common-subsequence` {
+
+    fun longestCommonSubsequence(text1: String, text2: String): Int {
+        return usingDP(text1, text2)
+    }
+
+    /**
+     * TC: O(2^(n + m)), SC: O(n + m) 시간초과!!!
+     */
+    private fun usingBruteForce(text1: String, text2: String): Int {
+
+        fun dfs(i: Int, j: Int): Int =
+            if (i == text1.length || j == text2.length) 0
+            else if(text1[i] == text2[j]) 1 + dfs(i + 1, j + 1)
+            else max(dfs(i + 1, j), dfs(i, j + 1))
+
+        return dfs(0, 0)
+    }
+
+    /**
+     * TC: O(n * m), SC: O(n * m)
+     */
+    private fun usingMemoization(text1: String, text2: String): Int {
+
+        fun dfs(i: Int, j: Int, memo: Array<IntArray>): Int {
+            if (i == text1.length || j == text2.length) return 0
+            else if (memo[i][j] != -1) return memo[i][j]
+
+            memo[i][j] = if(text1[i] == text2[j]) 1 + dfs(i + 1, j + 1, memo)
+            else max(dfs(i + 1, j, memo), dfs(i, j + 1, memo))
+
+            return memo[i][j]
+        }
+        val memo = Array(text1.length) { IntArray(text2.length) { -1 } }
+        return dfs(0, 0, memo)
+    }
+
+    /**
+     * TC: O(n * m), SC: O(n * m)
+     */
+    private fun usingDP(text1: String, text2: String): Int {
+        val dp = Array(text1.length + 1) { IntArray(text2.length + 1) }
+        for (i in text1.indices) {
+            for (j in text2.indices) {
+                dp[i + 1][j + 1] = if (text1[i] == text2[j]) dp[i][j] + 1
+                else max(dp[i + 1][j], dp[i][j + 1])
+            }
+        }
+        return dp[text1.length][text2.length]
+    }
+
+    @Test
+    fun `입력받은 두 문자열의 가장 긴 공통 부분 수열의 길이를 반환하라`() {
+        longestCommonSubsequence("abcde", "ace") shouldBe 3
+        longestCommonSubsequence("abc", "abc") shouldBe 3
+        longestCommonSubsequence("abcdefghi", "defi") shouldBe 4
+        longestCommonSubsequence("abc", "def") shouldBe 0
+    }
+}

longest-repeating-character-replacement/jdalma.kt

@@ -0,0 +1,62 @@
+package leetcode_study
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import kotlin.math.max
+
+class `longest-repeating-character-replacement` {
+
+    fun characterReplacement(s: String, k: Int): Int {
+        return usingSlidingWindow(s, k)
+    }
+
+    /**
+     * TC: O(n^3), SC: O(1) 시간초과 !!!
+     */
+    private fun usingBruteForce(s: String, k: Int): Int {
+        var result = 0
+
+        for (start in s.indices) {
+            for (end in start until s.length) {
+                val counter = mutableMapOf<Char, Int>()
+                for (i in start .. end) {
+                    counter[s[i]] = counter.getOrDefault(s[i], 0) + 1
+                }
+
+                val maxCount = counter.values.maxOrNull() ?: 0
+                if ((end - start + 1) - maxCount <= k) {
+                    result = max(result, end - start + 1)
+                }
+            }
+        }
+
+        return result
+    }
+
+    /**
+     * TC: O(n), SC: O(1)
+     */
+    private fun usingSlidingWindow(s: String, k: Int): Int {
+        var (maxLength, start) = 0 to 0
+        val count = IntArray(26)
+
+        for (end in s.indices) {
+            count[s[end] - 'A']++
+            while (end - start + 1 - count.max() > k) {
+                count[s[start] - 'A']--
+                start++
+            }
+            maxLength = max(end - start + 1, maxLength)
+        }
+
+        return maxLength
+    }
+
+    @Test
+    fun `문자열이 주어졌을 때 동일한 문자를 포함하는 가장 긴 부분 문자열의 길이를 반환한다 문자는 최대 k번 변경할 수 있다`() {
+        characterReplacement("ABAB", 2) shouldBe 4
+        characterReplacement("AABAB", 2) shouldBe 5
+        characterReplacement("AABAB", 1) shouldBe 4
+        characterReplacement("AABBAB", 1) shouldBe 4
+    }
+}

merge-two-sorted-lists/jdalma.kt

@@ -0,0 +1,45 @@
+package leetcode_study
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+
+class `merge-two-sorted-lists` {
+
+    data class ListNode(
+        var `val`: Int,
+        var next: ListNode? = null
+    )
+
+    /**
+     * TC: O(n + m), SC: O(1)
+     */
+    fun mergeTwoLists(list1: ListNode?, list2: ListNode?): ListNode? {
+        var (l1, l2) = list1 to list2
+        var current = ListNode(-1)
+        val result: ListNode = current
+
+        while (l1 != null && l2 != null) {
+            if (l1.`val` < l2.`val`) {
+                current.next = l1
+                l1 = l1.next
+            } else {
+                current.next = l2
+                l2 = l2.next
+            }
+            current.next?.let { current = it }
+        }
+
+        if (l1 != null) current.next = l1
+        if (l2 != null) current.next = l2
+
+        return result.next
+    }
+
+    @Test
+    fun `두 개의 리스트 노드를 정렬하여 병합한다`() {
+        mergeTwoLists(
+            ListNode(1,ListNode(2,ListNode(4))),
+            ListNode(1,ListNode(3,ListNode(4)))
+        ) shouldBe ListNode(1,ListNode(1,ListNode(2, ListNode(3, ListNode(4, ListNode(4))))))
+    }
+}