321. Create Maximum Number

    /*
     * 321. Create Maximum Number
     * 2016-7-6 by Mingyang
     */
     public int[] maxNumber(int[] nums1, int[] nums2, int k) {
        int n = nums1.length;
        int m = nums2.length;
        int[] ans = new int[k];
        for (int i = Math.max(0, k - m); i <= k && i <= n; ++i) {
            int[] candidate = merge(maxArray(nums1, i), maxArray(nums2, k - i), k);
            if (greater(candidate, 0, ans, 0))
                ans = candidate;
        }
        return ans;
    }

    private int[] merge(int[] nums1, int[] nums2, int k) {
        int[] ans = new int[k];
        for (int i = 0, j = 0, r = 0; r < k; ++r)
            ans[r] = greater(nums1, i, nums2, j) ? nums1[i++] : nums2[j++];
        return ans;
    }

    public boolean greater(int[] nums1, int i, int[] nums2, int j) {
        while (i < nums1.length && j < nums2.length && nums1[i] == nums2[j]) {
            i++;
            j++;
        }
        return j == nums2.length || (i < nums1.length && nums1[i] > nums2[j]);
    }

    public int[] maxArray(int[] nums, int k) {
        int n = nums.length;
        int[] ans = new int[k];
        for (int i = 0, j = 0; i < n; ++i) {
            while (n - i + j > k && j > 0 && ans[j - 1] < nums[i])
                j--;
            if (j < k)
                ans[j++] = nums[i];
        }
        return ans;
    }