2149-RearrangeArrayElementsBySign.go

package main

// 2149. Rearrange Array Elements by Sign
// You are given a 0-indexed integer array nums of even length consisting of an equal number of positive and negative integers.
// You should rearrange the elements of nums such that the modified array follows the given conditions:
// 		Every consecutive pair of integers have opposite signs.
// 		For all integers with the same sign, the order in which they were present in nums is preserved.
// 		The rearranged array begins with a positive integer.

// Return the modified array after rearranging the elements to satisfy the aforementioned conditions.

// Example 1:
// Input: nums = [3,1,-2,-5,2,-4]
// Output: [3,-2,1,-5,2,-4]
// Explanation:
// The positive integers in nums are [3,1,2]. The negative integers are [-2,-5,-4].
// The only possible way to rearrange them such that they satisfy all conditions is [3,-2,1,-5,2,-4].
// Other ways such as [1,-2,2,-5,3,-4], [3,1,2,-2,-5,-4], [-2,3,-5,1,-4,2] are incorrect because they do not satisfy one or more conditions.  

// Example 2:
// Input: nums = [-1,1]
// Output: [1,-1]
// Explanation:
// 1 is the only positive integer and -1 the only negative integer in nums.
// So nums is rearranged to [1,-1].
 
// Constraints:
// 		2 <= nums.length <= 2 * 10^5
// 		nums.length is even
// 		1 <= |nums[i]| <= 10^5
// 		nums consists of equal number of positive and negative integers.

import "fmt"

func rearrangeArray(nums []int) []int {
	res := make([]int,len(nums))
	// 初始化正数 / 负数位置  正数开头
	p_pos, n_pos := 0, 1 
	// for i := 0; i < len(nums); i = i + 1 {
	// 	if nums[i] > 0 {
	// 		res[p_pos] = nums[i]
	// 		p_pos += 2 // 步长为2
	// 	} else {
	// 		res[n_pos] = nums[i]
	// 		n_pos += 2 // 步长为2
	// 	}
	// }
	for _, n := range nums {
		if n > 0 {
			res[p_pos] = n
			p_pos += 2 // 步长为2
		} else {
			res[n_pos] = n
			n_pos += 2 // 步长为2
		}
	}
	return res
}

func main() {
	fmt.Println(rearrangeArray([]int{3,1,-2,-5,2,-4})) // [3,-2,1,-5,2,-4]
	fmt.Println(rearrangeArray([]int{-1,1})) // [1,-1]
}