Create Maximum Number LeetCode solution in C++

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class Solution {
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 public:
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  vector<int> maxArray(vector<int> &nums, int k) {
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    int n = nums.size();
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    stack<int> seen;
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    for (int i = 0; i < n; i++) {
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      int right = n - i - 1;
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      while (not seen.empty() and seen.top() < nums[i] and right + seen.size() >= k) seen.pop();
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      if (seen.size() < k) seen.push(nums[i]);
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    }
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    vector<int> res(k, 0);
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    for (int i = res.size() - 1; i >= 0; i--) {
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      res[i] = seen.top();
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      seen.pop();
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    }
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    return res;
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  }
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  bool greater(vector<int> &arr1, int i, vector<int> &arr2, int j) {
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    for (; i < arr1.size() and j < arr2.size(); i++, j++) {
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      if (arr1[i] == arr2[j]) continue;
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      return arr1[i] > arr2[j];
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    }
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    return i != arr1.size();
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  }
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  vector<int> merge(vector<int> &arr1, vector<int> &arr2) {
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    vector<int> res(arr1.size() + arr2.size());
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    for (int ind = 0, i = 0, j = 0; ind < res.size(); ind++) {
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      if (greater(arr1, i, arr2, j)) {
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        res[ind] = arr1[i];
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        i++;
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      } else {
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        res[ind] = arr2[j];
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        j++;
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      }
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    }
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    return res;
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  }
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  vector<int> maxNumber(vector<int> &nums1, vector<int> &nums2, int k) {
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    int m = nums1.size(), n = nums2.size();
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    vector<int> ans;
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    for (int len1 = max(0, k - n); len1 <= min(m, k); len1++) {
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      int len2 = k - len1;
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      vector<int> arr1 = maxArray(nums1, len1);
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      vector<int> arr2 = maxArray(nums2, len2);
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      vector<int> temp_res = merge(arr1, arr2);
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      if (greater(temp_res, 0, ans, 0)) {
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        ans.resize(temp_res.size());
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        for (int i = 0; i < temp_res.size(); i++) {
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          ans[i] = temp_res[i];
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        }
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      }
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    }
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    return ans;
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  }
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};