[Two Pointers][Container With Most Water] - Implement solution for Leetcode 11

2_two_pointers/4_container_with_most_water/solution.go

@@ -0,0 +1,60 @@
+package containerwithmostwater
+
+// Time complexity: O(n^2)
+// Space complexity: O(1)
+func MaxAreaBruteForce(heights []int) int {
+	n := len(heights)
+	maxArea := 0
+
+	for p1 := 0; p1 < n; p1++ {
+		for p2 := p1 + 1; p2 < n; p2++ {
+			height := heights[p1]
+			if heights[p2] < height {
+				height = heights[p2]
+			}
+			width := p2 - p1
+			area := height * width
+
+			if area > maxArea {
+				maxArea = area
+			}
+
+			// height := min(heights[p1], heights[p2])
+			// width := p2 - p1
+			// area := height * width
+			// maxArea = max(maxArea, area)
+		}
+	}
+	return maxArea
+}
+
+// Time complexity: O(n)
+// Space complexity: O(1)
+func MaxAreaTwoPointers(heights []int) int {
+	p1, p2, maxArea := 0, len(heights)-1, 0
+
+	for p1 < p2 {
+		height := heights[p1]
+		if heights[p2] < height {
+			height = heights[p2]
+		}
+		width := p2 - p1
+		area := height * width
+
+		if area > maxArea {
+			maxArea = area
+		}
+
+		// height := min(heights[p1], heights[p2])
+		// width := p2 - p1
+		// area := height * width
+		// maxArea = max(maxArea, area)
+
+		if heights[p1] < heights[p2] {
+			p1++
+		} else {
+			p2--
+		}
+	}
+	return maxArea
+}

2_two_pointers/4_container_with_most_water/solution_test.go

@@ -0,0 +1,37 @@
+package containerwithmostwater
+
+import "testing"
+
+func TestMaxArea(t *testing.T) {
+	cases := []struct {
+		name     string
+		fn       func([]int) int
+		heights  []int
+		expected int
+	}{
+		// MaxAreaBruteForce
+		{"BruteForce - Example 1", MaxAreaBruteForce, []int{1, 7, 2, 5, 4, 7, 3, 6}, 36},
+		{"BruteForce - Example 2", MaxAreaBruteForce, []int{2, 2, 2}, 4},
+		{"BruteForce - Minimal input size 2", MaxAreaBruteForce, []int{1, 1}, 1},
+		{"BruteForce - All zeroes", MaxAreaBruteForce, []int{0, 0, 0, 0}, 0},
+		{"BruteForce - Increasing heights", MaxAreaBruteForce, []int{1, 2, 3, 4, 5}, 6},
+		{"BruteForce - Decreasing heights", MaxAreaBruteForce, []int{5, 4, 3, 2, 1}, 6},
+
+		// MaxAreaTwoPointers
+		{"TwoPointers - Example 1", MaxAreaTwoPointers, []int{1, 7, 2, 5, 4, 7, 3, 6}, 36},
+		{"TwoPointers - Example 2", MaxAreaTwoPointers, []int{2, 2, 2}, 4},
+		{"TwoPointers - Minimal input size 2", MaxAreaTwoPointers, []int{1, 1}, 1},
+		{"TwoPointers - All zeroes", MaxAreaTwoPointers, []int{0, 0, 0, 0}, 0},
+		{"TwoPointers - Increasing heights", MaxAreaTwoPointers, []int{1, 2, 3, 4, 5}, 6},
+		{"TwoPointers - Decreasing heights", MaxAreaTwoPointers, []int{5, 4, 3, 2, 1}, 6},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got := c.fn(c.heights)
+			if got != c.expected {
+				t.Errorf("%s failed: expected %v, got %v", c.name, c.expected, got)
+			}
+		})
+	}
+}