628 finish

Author: aQua

Algorithms/0628.maximum-product-of-three-numbers/maximum-product-of-three-numbers.go

@@ -1,22 +1,37 @@
 package Problem0628
 
-import (
-	"sort"
-)
-
 func maximumProduct(nums []int) int {
-	sort.Ints(nums)
-	l := len(nums)
-	temp := append(nums[l-3:], nums[:3]...)
 
-	max := nums[0] * nums[1] * nums[2]
+	max := -1001
+	max1 := -1001
+	max2 := -1001
+	min1 := 1001
+	min2 := 1001
+
+	for _, n := range nums {
+		switch {
+		case n > max:
+			max2, max1, max = max1, max, n
+		case n > max1:
+			max2, max1 = max1, n
+		case n > max2:
+			max2 = n
+		}
 
-	for i := 0; i < len(temp)-3; i++ {
-		t := temp[i] * temp[i+1] * temp[i+2]
-		if max < t {
-			max = t
+		switch {
+		case n < min1:
+			min2, min1 = min1, n
+		case n < min2:
+			min2 = n
 		}
 	}
 
-	return max
+	return bigger(max1*max2, min1*min2) * max
+}
+
+func bigger(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
 }

Algorithms/0628.maximum-product-of-three-numbers/maximum-product-of-three-numbers_test.go

@@ -29,14 +29,19 @@ func Test_Problem0628(t *testing.T) {
 
 	qs := []question{
 		question{
-			para{[]int{-4, -3, -2, -1, 60}},
+			para{[]int{-4, -3, -2, -1, 1, 1, 1, 1, 1, 60}},
 			ans{720},
 		},
+
 		question{
 			para{[]int{1, 2, 3, 4}},
 			ans{24},
 		},
 
+		question{
+			para{[]int{1, 2, 3}},
+			ans{6},
+		},
 		// 如需多个测试，可以复制上方元素。
 	}