feat: 0238.Product-of-Array-Except-Self

Author: kimi0230

Leetcode/0238.Product-of-Array-Except-Self/README.md

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+---
+title: 238. Product of Array Except Self
+subtitle: "https://leetcode.com/problems/product-of-array-except-self/description/"
+date: 2024-02-19T18:01:00+08:00
+lastmod: 2024-02-19T18:01:00+08:00
+draft: false
+author: "Kimi.Tsai"
+authorLink: "https://kimi0230.github.io/"
+description: "0238.Product-of-Array-Except-Self"
+license: ""
+images: []
+
+tags: [LeetCode, Go, Medium, Product of Array Except Self]
+categories: [LeetCode]
+
+featuredImage: ""
+featuredImagePreview: ""
+
+hiddenFromHomePage: false
+hiddenFromSearch: false
+twemoji: false
+lightgallery: true
+ruby: true
+fraction: true
+fontawesome: true
+linkToMarkdown: false
+rssFullText: false
+
+toc:
+  enable: true
+  auto: true
+code:
+  copy: true
+  maxShownLines: 200
+math:
+  enable: false
+  # ...
+mapbox:
+  # ...
+share:
+  enable: true
+  # ...
+comment:
+  enable: true
+  # ...
+library:
+  css:
+    # someCSS = "some.css"
+    # located in "assets/"
+    # Or
+    # someCSS = "https://cdn.example.com/some.css"
+  js:
+    # someJS = "some.js"
+    # located in "assets/"
+    # Or
+    # someJS = "https://cdn.example.com/some.js"
+seo:
+  images: []
+  # ...
+---
+# [238. Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/description/)
+
+## 題目
+
+## 題目大意
+
+
+## 解題思路
+
+## Big O
+時間複雜 : ``
+空間複雜 : ``
+
+## 來源
+* https://leetcode.com/problems/product-of-array-except-self/description/
+* https://leetcode.cn/problems/product-of-array-except-self/description/
+
+## 解答
+https://github.com/kimi0230/LeetcodeGolang/blob/master/Leetcode/0238.Product-of-Array-Except-Self/main.go
+
+```go
+
+```
+
+##  Benchmark
+
+```sh
+
+```

Leetcode/0238.Product-of-Array-Except-Self/main.go

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+package productofarrayexceptself
+
+// 時間複雜 O(), 空間複雜 O()
+func productExceptSelf(nums []int) []int {
+	result, left, right := make([]int, len(nums)), make([]int, len(nums)), make([]int, len(nums))
+
+	// left 為左側所有的成績
+	// 索引為'0' 的元素, 因為左側沒有元素,所以left[0]=1
+	left[0] = 1
+	for i := 1; i < len(nums); i++ {
+		left[i] = left[i-1] * nums[i-1]
+	}
+
+	right[len(nums)-1] = 1
+	for i := len(nums) - 2; i >= 0; i-- {
+		right[i] = right[i+1] * nums[i+1]
+	}
+
+	for i := 0; i < len(nums); i++ {
+		result[i] = left[i] * right[i]
+	}
+	return result
+}
+
+func productExceptSelf2(nums []int) []int {
+	result := make([]int, len(nums))
+
+	result[0] = 1
+	for i := 1; i < len(nums); i++ {
+		result[i] = result[i-1] * nums[i-1]
+	}
+
+	rightProduct := 1
+	for i := len(nums) - 1; i >= 0; i-- {
+		result[i] = result[i] * rightProduct
+		rightProduct = rightProduct * nums[i]
+	}
+
+	return result
+}

Leetcode/0238.Product-of-Array-Except-Self/main_test.go

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+package productofarrayexceptself
+
+import (
+	"reflect"
+	"testing"
+)
+
+var tests = []struct {
+	arg1 []int
+	want []int
+}{
+	{
+		[]int{1, 2, 3, 4},
+		[]int{24, 12, 8, 6},
+	},
+}
+
+func TestProductExceptSelf(t *testing.T) {
+	for _, tt := range tests {
+		if got := productExceptSelf(tt.arg1); !reflect.DeepEqual(got, tt.want) {
+			// if got := productExceptSelf(tt.arg1); got != tt.want {
+			t.Errorf("got = %v, want = %v", got, tt.want)
+		}
+	}
+}
+
+func BenchmarkProductExceptSelf(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		productExceptSelf(tests[0].arg1)
+	}
+}
+
+func TestProductExceptSelf2(t *testing.T) {
+	for _, tt := range tests {
+		if got := productExceptSelf2(tt.arg1); !reflect.DeepEqual(got, tt.want) {
+			// if got := productExceptSelf2(tt.arg1); got != tt.want {
+			t.Errorf("got = %v, want = %v", got, tt.want)
+		}
+	}
+}
+
+func BenchmarkProductExceptSelf2(b *testing.B) {
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		productExceptSelf2(tests[0].arg1)
+	}
+}
+
+/*
+go test -benchmem -run=none LeetcodeGolang/Leetcode/0238.Product-of-Array-Except-Self -bench=.
+goos: darwin
+goarch: amd64
+pkg: LeetcodeGolang/Leetcode/0238.Product-of-Array-Except-Self
+cpu: Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
+BenchmarkProductExceptSelf-8            12772174               158.4 ns/op            96 B/op          3 allocs/op
+BenchmarkProductExceptSelf2-8           32292304                63.74 ns/op           32 B/op          1 allocs/op
+PASS
+ok      LeetcodeGolang/Leetcode/0238.Product-of-Array-Except-Self       4.228s
+*/