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class Solution {
public:
    vector<int> rearrangeArray(vector<int>& nums) {
        sort(nums.begin(), nums.end());
        int n=nums.size();
        vector<int> res(n, 0);
        int i = 0;
        for(int nn:nums){
            res[i] = nn;
            i += 2;
            if(i>=n)
                i=1;
        }
        return res;
    }
};
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    vector<int> rearrangeArray(vector<int>& A) {
        sort(A.begin(), A.end());
        for (int i = 1; i < A.size(); i += 2)
            swap(A[i], A[i - 1]);
        return A;
    }

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vector<int> rearrangeArray(vector<int>& nums) {
        int n = nums.size();

        // Find a median.
        auto midptr = nums.begin() + n / 2;
        nth_element(nums.begin(), midptr, nums.end());
        int mid = *midptr;

        // Index-rewiring.
        #define A(i) nums[(1+2*(i)) % (n|1)]

        // 3-way-partition-to-wiggly in O(n) time with O(1) space.
        int i = 0, j = 0, k = n - 1;
        while (j <= k) {
            if (A(j) > mid)
                swap(A(i++), A(j++));
            else if (A(j) < mid)
                swap(A(j), A(k--));
            else
                j++;
        }
        return nums;
    }
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