문제 추가

Author: jdalma

maximum-subarray/jdalma.kt

@@ -0,0 +1,48 @@
+package leetcode_study
+
+import io.kotest.matchers.shouldBe
+import org.junit.jupiter.api.Test
+import kotlin.math.max
+
+class `maximum-subarray` {
+
+    fun maxSubArray(nums: IntArray): Int {
+        return usingDP(nums)
+    }
+
+    /**
+     * TC: O(n), SC: O(n)
+     */
+    private fun usingDP(nums: IntArray): Int {
+        val dp = IntArray(nums.size).apply {
+            this[0] = nums[0]
+        }
+
+        for (index in 1 until nums.size) {
+            dp[index] = max(nums[index], nums[index] + dp[index - 1])
+        }
+
+        return dp.max()
+    }
+
+    /**
+     * TC: O(n), SC: O(1)
+     */
+    private fun usingKadane(nums: IntArray): Int {
+        var (current, max) = nums[0] to nums[0]
+
+        for (index in 1 until nums.size) {
+            current = max(nums[index], current + nums[index])
+            max = max(max, current)
+        }
+
+        return max
+    }
+
+    @Test
+    fun `정수 배열의 하위 배열 중 가장 큰 합을 반환한다`() {
+        maxSubArray(intArrayOf(-2,1,-3,4,-1,2,1,-5,4)) shouldBe 6
+        maxSubArray(intArrayOf(1)) shouldBe 1
+        maxSubArray(intArrayOf(5,4,-1,7,8)) shouldBe 23
+    }
+}