238 adding

Author: aQua

Algorithms/0238.product-of-array-except-self/README.md

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+# [238. Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/)
+
+## 题目
+Given an array of n integers where n > 1, nums, return an array output such that output[i] is equal to the product of all the elements of nums except nums[i].
+
+Solve it without division and in O(n).
+
+For example, given [1,2,3,4], return [24,12,8,6].
+
+Follow up:
+Could you solve it with constant space complexity? (Note: The output array does not count as extra space for the purpose of space complexity analysis.)
+
+## 解题思路
+
+见程序注释

Algorithms/0238.product-of-array-except-self/product-of-array-except-self.go

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+package Problem0238
+
+func productExceptSelf(a []int) []int {
+	l := len(a)
+	res := make([]int, l)
+
+	p := 1
+	zero := 0
+	for i := 0; i < l; i++ {
+		if a[i] == 0 {
+			zero++
+			continue
+		}
+		p *= a[i]
+	}
+
+	if zero > 1 {
+		return res
+	}
+
+	for i := 0; i < l; i++ {
+		if a[i] != 0 {
+			res[i] = p / a[i]
+		}
+	}
+
+	return res
+}

Algorithms/0238.product-of-array-except-self/product-of-array-except-self_test.go

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+package Problem0238
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type question struct {
+	para
+	ans
+}
+
+// para 是参数
+type para struct {
+	nums []int
+}
+
+// ans 是答案
+type ans struct {
+	one []int
+}
+
+func Test_Problem0238(t *testing.T) {
+	ast := assert.New(t)
+
+	qs := []question{
+
+		question{
+			para{
+				[]int{1, 2, 3, 4},
+			},
+			ans{
+				[]int{24, 12, 8, 6},
+			},
+		},
+
+		question{
+			para{
+				[]int{0, 0, 0, 0},
+			},
+			ans{
+				[]int{0, 0, 0, 0},
+			},
+		},
+
+		// 如需多个测试，可以复制上方元素。
+	}
+
+	for _, q := range qs {
+		a, p := q.ans, q.para
+		fmt.Printf("~~%v~~\n", p)
+
+		ast.Equal(a.one, productExceptSelf(p.nums), "输入:%v", p)
+	}
+}