9058 finish

Author: aQuaYi

Algorithms/0905.sort-array-by-parity/README.md

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+# [905. Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity/)
+
+## 题目
+
+Given an array `A` of non-negative integers, return an array consisting of all the even elements of `A`, followed by all the odd elements of `A`.
+
+You may return any answer array that satisfies this condition.
+
+Example 1:
+
+```text
+Input: [3,1,2,4]
+Output: [2,4,3,1]
+The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.
+```
+
+Note:
+
+- 1 <= A.length <= 5000
+- 0 <= A[i] <= 5000
+
+## 解题思路
+
+见程序注释

Algorithms/0905.sort-array-by-parity/sort-array-by-parity.go

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+package problem0905
+
+func sortArrayByParity(a []int) []int {
+	i, j, size := 0, len(a)-1, len(a)
+	for i < j {
+		for i < size && a[i]%2 == 0 {
+			i++
+		}
+		for i < j && a[j]%2 == 1 {
+			j--
+		}
+		if i < j {
+			a[i], a[j] = a[j], a[i]
+		}
+	}
+	return a
+}

Algorithms/0905.sort-array-by-parity/sort-array-by-parity_test.go

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+package problem0905
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// tcs is testcase slice
+var tcs = []struct {
+	A []int
+}{
+
+	{
+		[]int{3, 1, 2, 4},
+	},
+
+	// 可以有多个 testcase
+}
+
+func split(a []int) (evens, odds []int) {
+	size := len(a)
+	var i int
+	for i = 0; i < size; i++ {
+		if a[i]%2 == 1 {
+			break
+		}
+	}
+	return a[:i], a[i:]
+}
+
+func isAllEven(a []int) bool {
+	for _, n := range a {
+		if n%2 == 1 {
+			return false
+		}
+	}
+	return true
+}
+
+func isAllOdd(a []int) bool {
+	for _, n := range a {
+		if n%2 == 0 {
+			return false
+		}
+	}
+	return true
+}
+
+func Test_sortArrayByParity(t *testing.T) {
+	ast := assert.New(t)
+
+	for _, tc := range tcs {
+		fmt.Printf("~~%v~~\n", tc)
+		ans := sortArrayByParity(tc.A)
+		evens, odds := split(ans)
+		ast.True(isAllEven(evens))
+		ast.True(isAllOdd(odds))
+	}
+}
+
+func Benchmark_sortArrayByParity(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range tcs {
+			sortArrayByParity(tc.A)
+		}
+	}
+}