Wiggle Sort 508

Question

Given an unsorted array nums, reorder it in-place such that

nums[0] <= nums[1] >= nums[2] <= nums[3]....

Notice

Please complete the problem in-place.

Example

Given nums = [3, 5, 2, 1, 6, 4], one possible answer is [1, 6, 2, 5, 3, 4].

Solution

偶数位要小，奇数位要大。遍历数组，若走到偶数位时，若其大于前一位数，则和前一位交换；若走到奇数位，若其比前一位要小，则和前一位交换。

代码如下：

public class Solution {
    /**
     * @param nums a list of integer
     * @return void
     */
    public void wiggleSort(int[] nums) {
        // Write your code here
        if(nums == null || nums.length <= 1){
            return;
        }

        for(int i = 1; i < nums.length; i++){
            if((i % 2 == 1 && nums[i] < nums[i - 1]) || (i % 2 == 0 && nums[i] > nums[i - 1])){
                int temp = nums[i - 1];
                nums[i - 1] = nums[i];
                nums[i] = temp;
            }
        }
    }
}