相鄰元素的和&頭尾元素兩兩配對_初學vector對象

讀一組整數到 vector 對象，計算並輸出每對相鄰元素的和。如果讀入元素個數爲奇數，則提示用戶最後一個元素沒有求和，並輸出其值。然後修改程序：頭尾元素兩兩配對（第一個和最後一個，第二個和倒數第二個，以此類推），計算每對元素的和，並輸出。

#include <iostream>
#include <vector>
#include <string>
using namespace std;

int main()
{
	vector<int> vt;
	vector<int> sidesum;
	vector<int> firstlast;
	int ival;

	//讀入數據到vector對象中。
	cout<<"Enter numbers(Ctrl+z to end):"<<endl;
	while (cin>>ival)
	{
		vt.push_back(ival);
	}

	//計算相鄰元素的和並輸出
	if(vt.size()==0)
	{
		cout<<"No element !"<<endl;
		return -1;
	}
	cout<<"Sum of each pair of adjacent elements in the vector:"
		<<endl;

	cout<<"\t\t******* side bye side sum ******* "<<endl;
	for (vector<int>::size_type i=0;i<vt.size()-1;i=i+2)
	{
		cout<<vt[i]+vt[i+1]<<'\t';
		if ((i+2)%12==0)
		{
			cout<<endl;
		}
	}
	cout<<endl;
	cout<<endl;
	if (vt.size()%2!=0)
	{
		cout<<endl
			<<"The last element is no been summed "
			<<"and it`s value is "
			<<vt[vt.size()-1]<<endl;
	}

	cout<<"\t\t******* First and Last sum ******* "<<endl;
	for (vector<int>::size_type i=0;i<vt.size()/2;++i)
	{
		cout<<vt[i]+vt[vt.size()-i-1]<<'\t';
		if ((i+1)%6==0)
		{
			cout<<endl;
		}
	}

	if (vt.size()%2!=0)
	{
		cout<<endl
			<<"The middle element is no been summed "
			<<"and it`s value is "
			<<vt[vt.size()/2]<<endl;
	}
	return 0;
}