From 49fa7539e1ee3d33b73217dbe68b373236b51473 Mon Sep 17 00:00:00 2001
From: s50600822 <s50600822@gmail.com>
Date: Sun, 5 Nov 2023 14:12:14 +1100
Subject: [PATCH] https://leetcode.com/problems/maximum-subarray/

---
 .../main/java/hoa/can/code/med/MaxSubArr.java | 21 +++++++++++++++++++
 .../java/hoa/can/code/MaxSubArrSumTest.java   | 19 +++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 interview_prep/algorithm/java/src/main/java/hoa/can/code/med/MaxSubArr.java
 create mode 100644 interview_prep/algorithm/java/src/test/java/hoa/can/code/MaxSubArrSumTest.java

diff --git a/interview_prep/algorithm/java/src/main/java/hoa/can/code/med/MaxSubArr.java b/interview_prep/algorithm/java/src/main/java/hoa/can/code/med/MaxSubArr.java
new file mode 100644
index 00000000..04309169
--- /dev/null
+++ b/interview_prep/algorithm/java/src/main/java/hoa/can/code/med/MaxSubArr.java
@@ -0,0 +1,21 @@
+package hoa.can.code.med;
+
+/**
+ * <a href="https://leetcode.com/problems/maximum-subarray/">desc</a>
+ */
+public class MaxSubArr {
+    public int maxSubArray(int[] nums) {
+        int maxSoFar = Integer.MIN_VALUE;
+        int maxEndingAt = 0;
+        for (int num : nums) {
+            maxEndingAt = maxEndingAt + num;
+            if (maxSoFar < maxEndingAt) {
+                maxSoFar = maxEndingAt;
+            }
+            if (maxEndingAt < 0) {
+                maxEndingAt = 0;
+            }
+        }
+        return maxSoFar;
+    }
+}
diff --git a/interview_prep/algorithm/java/src/test/java/hoa/can/code/MaxSubArrSumTest.java b/interview_prep/algorithm/java/src/test/java/hoa/can/code/MaxSubArrSumTest.java
new file mode 100644
index 00000000..93fb02e9
--- /dev/null
+++ b/interview_prep/algorithm/java/src/test/java/hoa/can/code/MaxSubArrSumTest.java
@@ -0,0 +1,19 @@
+package hoa.can.code;
+
+import hoa.can.code.ez.LongestPalindrome;
+import hoa.can.code.med.MaxSubArr;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class MaxSubArrSumTest {
+    MaxSubArr tst = new MaxSubArr();
+    @Test
+    @DisplayName("max sub arr sum")
+    public void test(){
+        assertEquals(1, tst.maxSubArray(new int[]{1}));
+        assertEquals(6, tst.maxSubArray(new int[]{-2,1,-3,4,-1,2,1,-5,4}));
+        assertEquals(23, tst.maxSubArray(new int[]{5,4,-1,7,8}));
+    }
+}