add 628 solution

Author: 6boris

src/0628.Maximum-Product-of-Three-Numbers/README.md

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+# [628. Maximum Product of Three Numbers][title]
+
+## Description
+
+Given an integer array, find three numbers whose product is maximum and output the maximum product.
+**Example 1:**
+
+```
+Input: a = "11", b = "1"
+Output: "100"
+```
+
+**Example 2:**
+
+```
+Input: a = "1010", b = "1011"
+Output: "10101"
+```
+
+**Tags:** Math, String
+
+## 题意
+> 求2数之和
+
+## 题解
+
+### 思路1
+> 三个数的最大乘积，必然是三个最大的数的乘积或者两个最小的（负）数与最大数的乘积。
+  通过线性扫描或者排序找出最大的三个数和最小的两个数即可。
+
+时间复杂
+线性扫描的时间复杂度是 O(n)O(n)；排序的时间复杂度是 O(nlogn)O(nlog⁡n)。
+
+```go
+func maximumProduct(nums []int) int {
+	sort.Ints(nums)
+	n := len(nums)
+	return max(nums[n-1]*nums[n-2]*nums[n-3], nums[n-1]*nums[0]*nums[1])
+}
+```
+
+### 思路2
+> 思路2
+```go
+
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-leetcode][me]
+
+[title]: https://leetcode.com/problems/maximum-product-of-three-numbers/
+[me]: https://github.com/kylesliu/awesome-golang-leetcode

src/0628.Maximum-Product-of-Three-Numbers/Solution.go

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+package Solution
+
+import (
+	"sort"
+)
+
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
+
+// 暴力排序解法
+func maximumProduct(nums []int) int {
+	sort.Ints(nums)
+	n := len(nums)
+	return max(nums[n-1]*nums[n-2]*nums[n-3], nums[n-1]*nums[0]*nums[1])
+}
+
+// 桶排序排序 O(N)
+func maximumProduct2(nums []int) int {
+	max1, max2, max3, min1, min2 := -1001, -1001, -1001, 1001, 1001
+
+	for _, v := range nums {
+		if v > max1 {
+			max3 = max2
+			max2 = max1
+			max1 = v
+		} else if v > max2 {
+			max3 = max2
+			max2 = v
+		} else if v > max3 {
+			max3 = v
+		}
+
+		if v < min1 {
+			min2 = min1
+			min1 = v
+		} else if v < min2 {
+			min2 = v
+		}
+
+	}
+	return max(max1*min1*min2, max1*max2*max3)
+}

src/0628.Maximum-Product-of-Three-Numbers/Solution_test.go

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+package Solution
+
+import (
+	"reflect"
+	"strconv"
+	"testing"
+)
+
+func TestSolution(t *testing.T) {
+	//	测试用例
+	cases := []struct {
+		name   string
+		inputs []int
+		expect int
+	}{
+		{"TestCase", []int{1, 2, 3}, 6},
+		{"TestCase", []int{1, 2, 3, 4}, 24},
+	}
+
+	//	开始测试
+	for i, c := range cases {
+		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
+			got := maximumProduct(c.inputs)
+			if !reflect.DeepEqual(got, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
+					c.expect, got, c.inputs)
+			}
+		})
+	}
+}
+
+func TestSolution2(t *testing.T) {
+	//	测试用例
+	cases := []struct {
+		name   string
+		inputs []int
+		expect int
+	}{
+		{"TestCase", []int{1, 2, 3}, 6},
+		{"TestCase", []int{1, 2, 3, 4}, 24},
+	}
+
+	//	开始测试
+	for i, c := range cases {
+		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
+			got := maximumProduct2(c.inputs)
+			if !reflect.DeepEqual(got, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
+					c.expect, got, c.inputs)
+			}
+		})
+	}
+}
+
+//	压力测试
+func BenchmarkSolution(b *testing.B) {
+
+}
+
+//	使用案列
+func ExampleSolution() {
+
+}