feat: add ContainerWithMostWater algorithm with tests

src/main/java/com/thealgorithms/misc/ContainerWithMostWater.java

@@ -0,0 +1,32 @@
+package com.thealgorithms.misc;
+
+/**
+ * Finds the maximum amount of water a container can store given an array of
+ * heights. Uses a two-pointer approach starting from both ends.
+ *
+ * <p>Example: height = [1,8,6,2,5,4,8,3,7] -> 49
+ *
+ * <p>Time complexity: O(n), Space complexity: O(1)
+ *
+ * @see <a href="https://leetcode.com/problems/container-with-most-water/">LeetCode #11</a>
+ */
+public final class ContainerWithMostWater {
+    private ContainerWithMostWater() {
+    }
+
+    public static int maxArea(int[] height) {
+        int left = 0;
+        int right = height.length - 1;
+        int maxWater = 0;
+        while (left < right) {
+            int water = Math.min(height[left], height[right]) * (right - left);
+            maxWater = Math.max(maxWater, water);
+            if (height[left] < height[right]) {
+                left++;
+            } else {
+                right--;
+            }
+        }
+        return maxWater;
+    }
+}

src/test/java/com/thealgorithms/misc/ContainerWithMostWaterTest.java

@@ -0,0 +1,28 @@
+package com.thealgorithms.misc;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class ContainerWithMostWaterTest {
+
+    @Test
+    public void testExample() {
+        assertEquals(49, ContainerWithMostWater.maxArea(new int[] {1, 8, 6, 2, 5, 4, 8, 3, 7}));
+    }
+
+    @Test
+    public void testTwoElements() {
+        assertEquals(1, ContainerWithMostWater.maxArea(new int[] {1, 1}));
+    }
+
+    @Test
+    public void testDescending() {
+        assertEquals(4, ContainerWithMostWater.maxArea(new int[] {4, 3, 2, 1}));
+    }
+
+    @Test
+    public void testEqualHeights() {
+        assertEquals(8, ContainerWithMostWater.maxArea(new int[] {2, 2, 2, 2, 2}));
+    }
+}