977. 有序数组的平方
难度简单 209
给你一个按 非递减顺序 排序的整数数组 nums,返回 每个数字的平方组成的新数组,要求也按 非递减顺序 排序。
示例 1:
输入:nums = [-4,-1,0,3,10]
输出:[0,1,9,16,100]
解释:平方后,数组变为 [16,1,0,9,100]
排序后,数组变为 [0,1,9,16,100]
双指针
    public int[] sortedSquares(int[] nums) {
        int n = nums.length;
        int[] ans = new int[n];
        for (int i = 0, j = n - 1, pos = n - 1; i <= j;) {
            if (nums[i] * nums[i] > nums[j] * nums[j]) {
                ans[pos] = nums[i] * nums[i];
                ++i;
            } else {
                ans[pos] = nums[j] * nums[j];
                --j;
            }
            --pos;
        }
        return ans;
    }
作者:LeetCode-Solution
链接:https://leetcode-cn.com/problems/squares-of-a-sorted-array/solution/you-xu-shu-zu-de-ping-fang-by-leetcode-solution/
平方再排序
public int[] sortedSquares(int[] nums) {
        int[] ans = new int[nums.length];
        for (int i = 0; i < nums.length; ++i) {
            ans[i] = nums[i] * nums[i];
        }
        Arrays.sort(ans);
        return ans;
    }
作者:LeetCode-Solution
链接:https://leetcode-cn.com/problems/squares-of-a-sorted-array/solution/you-xu-shu-zu-de-ping-fang-by-leetcode-solution/