LeetCode 667. 优美的排列 II Beautiful Arrangement II (Medium)

class Solution {
public:
    vector<int> constructArray(int n, int k) {

        vector<int> ret(n);
        ret[0] = 1;
        //构造k个不同的差值
        for (int i = 1, interval = k; i <= k; ++i, --interval)
            ret[i] = i % 2 == 1 ? (ret[i - 1] + interval) : (ret[i - 1] - interval);
        //从k+1补到n
        for (int i = k + 1; i < n; ++i)
            ret[i] = i + 1;
        
        return ret;
    }
};