2022-04-27：Alice 有一个下标从 0 开始的数组 arr ，由 n 个正整数组成。她会选择一个任意的 正整数 k 并按下述方式创建两个下标从 0

fn main() {
    let mut nums: Vec<isize> = vec![2, 10, 6, 4, 8, 12];
    let ans: Vec<isize> = recover_array(&mut nums);
    println!("ans = {:?}", ans);
}

fn recover_array(nums: &mut Vec<isize>) -> Vec<isize> {
    nums.sort_by(|a, b| a.cmp(&b));
    let n = nums.len() as isize;
    // nums[0] -> 小数组的第0个
    let m = n >> 1;
    // 谁是大数组的第0个？不知道，试！first位置的数！
    for first in 1..=m {
        // d = 2 * k; k正数！
        let d = nums[first as usize] - nums[0];
        if d > 0 && (d & 1) == 0 {
            // 试图生成原始数组！ans！
            let mut ans: Vec<isize> = vec![];
            for _k in 0..m {
                ans.push(0);
            }
            let mut i: isize = 0;
            let mut set: Vec<bool> = vec![];
            for _k in 0..n {
                set.push(false);
            }
            let k: isize = d >> 1;
            let mut l: isize = 0;
            let mut r: isize = first;
            while r < n {
                while set[l as usize] {
                    l += 1;
                }
                if l == r {
                    r += 1;
                } else if nums[r as usize] - nums[l as usize] > d {
                    break;
                } else if nums[r as usize] - nums[l as usize] < d {
                    r += 1;
                } else {
                    set[r as usize] = true;
                    r += 1;
                    ans[i as usize] = nums[l as usize] + k;
                    l += 1;
                    i += 1;
                }
            }
            if i == m {
                return ans;
            }
        }
    }
    return vec![];
}