Add: Maximum Product of Three Numbers

Author: openset

problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers.go

@@ -1 +1,27 @@
 package maximum_product_of_three_numbers
+
+import "math"
+
+func maximumProduct(nums []int) int {
+	min1, min2 := math.MaxInt32, math.MaxInt32
+	max1, max2, max3 := math.MinInt32, math.MinInt32, math.MinInt32
+	for _, n := range nums {
+		if n < min1 {
+			min1, min2 = n, min1
+		} else if n < min2 {
+			min2 = n
+		}
+		if n > max3 {
+			max1, max2, max3 = max2, max3, n
+		} else if n > max2 {
+			max1, max2 = max2, n
+		} else if n > max1 {
+			max1 = n
+		}
+	}
+	ans1, ans2 := min1*min2*max3, max1*max2*max3
+	if ans1 > ans2 {
+		return ans1
+	}
+	return ans2
+}

problems/maximum-product-of-three-numbers/maximum_product_of_three_numbers_test.go

@@ -1 +1,31 @@
 package maximum_product_of_three_numbers
+
+import "testing"
+
+type caseType struct {
+	input    []int
+	expected int
+}
+
+func TestMaximumProduct(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input:    []int{1, 2, 3},
+			expected: 6,
+		},
+		{
+			input:    []int{1, 2, 3, 4},
+			expected: 24,
+		},
+		{
+			input:    []int{-2, -1, 0, 2, 3},
+			expected: 6,
+		},
+	}
+	for _, tc := range tests {
+		output := maximumProduct(tc.input)
+		if output != tc.expected {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
+		}
+	}
+}