442 finish

Author: aQua

Algorithms/0442.find-all-duplicates-in-an-array/README.md

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+# [442. Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array/)
+
+## 题目
+Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.
+
+Find all the elements that appear twice in this array.
+
+Could you do it without extra space and in O(n) runtime?
+
+Example:
+```
+Input:
+[4,3,2,7,8,2,3,1]
+Output:
+[2,3]
+```
+## 解题思路
+
+见程序注释

Algorithms/0442.find-all-duplicates-in-an-array/find-all-duplicates-in-an-array.go

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+package Problem0442
+
+import (
+	"sort"
+)
+
+func findDuplicates(a []int) []int {
+	for i := 0; i < len(a); i++ {
+		for a[i] != a[a[i]-1] {
+			a[i], a[a[i]-1] = a[a[i]-1], a[i]
+		}
+	}
+
+	res := make([]int, 0, len(a))
+
+	for i, n := range a {
+		if i != n-1 {
+			res = append(res, n)
+		}
+	}
+
+	sort.Ints(res)
+
+	return res
+}

Algorithms/0442.find-all-duplicates-in-an-array/find-all-duplicates-in-an-array_test.go

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+package Problem0442
+
+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_Problem0442(t *testing.T) {
+	ast := assert.New(t)
+
+	qs := []question{
+
+		question{
+			para{
+				[]int{4, 3, 2, 7, 8, 2, 3, 1},
+			},
+			ans{
+				[]int{2, 3},
+			},
+		},
+
+		// 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, findDuplicates(p.nums), "输入:%v", p)
+	}
+}