# Easy to understand C++ solution to Create Maximum Number

• ``````    /*
To get the maximal number out of two vector, we can split the problem into:
1) create the maximal number of length i from one vector
2) merge number1 of length(i) and number2 of length(k-i)

*/

//return the maximal number of len k
vector<int>MaxNumLenk(vector<int>nums, int k)
{
int maxDrop = nums.size()-k;
vector<int>res;
for(auto n:nums){
//insert nums[i] and make sure nums[i] is the smallest
while(maxDrop && res.size() && res.back() < n){
res.pop_back();
maxDrop--;
}
res.push_back(n);
}
res.resize(k);
return res;
}
//merge two vector to get the maximal number of lengtg k
vector<int> Merge(vector<int>nums1, vector<int>nums2)
{
vector<int>res;
while(nums1.size() + nums2.size()){
//lexi compare
vector<int>& temp = nums1>nums2?nums1:nums2;
res.push_back(temp[0]);
temp.erase(temp.begin());
}
return res;
}

vector<int> maxNumber(vector<int>& nums1, vector<int>& nums2, int k)
{
int n1 = nums1.size(), n2 = nums2.size();
vector<int>maxNum(k,INT_MIN), temp1, temp2, merged;
for(int i = max(k-n2, 0); i<= min(n1,k); i++){
// i element from nums1, k-i from nums2
temp1 = MaxNumLenk(nums1, i);
temp2 = MaxNumLenk(nums2, k-i);
merged = Merge(temp1, temp2);
maxNum = max(maxNum, merged);
}
return maxNum;
}``````

• Fascinating how similar this is to my solution...

"Yours":

``````vector<int>MaxNumLenk(vector<int>nums, int k)
{
int maxDrop = nums.size()-k;
vector<int>res;
for(auto n:nums){
while(maxDrop && res.size() && res.back() < n){
res.pop_back();
maxDrop--;
}
res.push_back(n);
}
res.resize(k);
return res;
}
``````

Mine:

``````vector<int> maxNumber(vector<int> nums, int k) {
int drop = nums.size() - k;
vector<int> out;
for (int num : nums) {
while (drop && out.size() && out.back() < num) {
out.pop_back();
drop--;
}
out.push_back(num);
}
out.resize(k);
return out;
}
``````

"Yours":

``````vector<int> Merge(vector<int>nums1, vector<int>nums2)
{
vector<int>res;
while(nums1.size() + nums2.size()){
vector<int>& temp = nums1>nums2?nums1:nums2;
res.push_back(temp[0]);
temp.erase(temp.begin());
}
return res;
}
``````

Mine:

``````vector<int> maxNumber(vector<int> nums1, vector<int> nums2) {
vector<int> out;
while (nums1.size() + nums2.size()) {
vector<int>& now = nums1 > nums2 ? nums1 : nums2;
out.push_back(now[0]);
now.erase(now.begin());
}
return out;
}
``````

"Yours":

``````vector<int> maxNumber(vector<int>& nums1, vector<int>& nums2, int k)
{
int n1 = nums1.size(), n2 = nums2.size();
vector<int>maxNum(k,INT_MIN), temp1, temp2, merged;
for(int i = max(k-n2, 0); i<= min(n1,k); i++){
temp1 = MaxNumLenk(nums1, i);
temp2 = MaxNumLenk(nums2, k-i);
merged = Merge(temp1, temp2);
maxNum = max(maxNum, merged);
}
return maxNum;
}
``````

Mine:

``````vector<int> maxNumber(vector<int>& nums1, vector<int>& nums2, int k) {
int n1 = nums1.size(), n2 = nums2.size();
vector<int> best;
for (int k1=max(k-n2, 0); k1<=min(k, n1); ++k1)
best = max(best, maxNumber(maxNumber(nums1, k1),
maxNumber(nums2, k-k1)));
return best;
}``````

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