【介绍】

【头文件】

#include<algorithm>

【作用】

Template :
template 
  outiter merge (initer1 beg1, initer1 end1,
                        initer2 beg2, initer2 end2,
                        outiter res)

Parameters :
beg1 :  Input iterator to initial position of first sequence.
end1 :  Input iterator to final position of first sequence.

beg2 :  Input iterator to initial position of second sequence.
end2 :  Input iterator to final position of second sequence.

res : Output Iterator to initial position of resultant container.
Return value : 
Iterator to last element of the resulting container.

// using merge() to merge the initial containers
merge(arr1.begin(), arr1.end(), arr2.begin(), arr2.end(), arr3.begin());

Template :
template 
  outiter merge (initer1 beg1, initer1 end1,
                        initer2 beg2, initer2 end2,
                        outiter res, Compare comp)

Parameters :
beg1 :  Input iterator to initial position of first sequence.
end1 :  Input iterator to final position of first sequence.

beg2 :  Input iterator to initial position of second sequence.
end2 :  Input iterator to final position of second sequence.

res : Output Iterator to initial position of resultant container.
comp : The comparator function that returns a boolean
true/false of the each elements compared. This function 
accepts two arguments. This can be function pointer or 
function object and cannot change values.
Return value : 
Iterator to last element of the resulting container.

// comparator function to reverse merge sort
struct greaters {
    bool operator()(const long& a, const long& b) const
    {
        return a > b;
    }
};


    // using merge() to merge the initial containers
    // returns descended merged container
    merge(arr1.begin(), arr1.end(), arr2.begin(), arr2.end(), arr3.begin(), greaters());

【任务】