多项式的一种特殊解法

#include<iostream>
#include<vector>
#include<ctime>
#include<cmath>
using namespace std;

//多项式解法 y= 1+2*x+3*x^2+......
void main()
{
	clock_t start = clock();
	//提出x的解法
	int n;
	int x;
	cin >> n >> x;
	vector<int> a;
	for (int i = 1; i <= n; i++)
	{
		a.push_back(i);
	}
	int p = a[n-1];
	for (int i = n; i>=2; i--)
	{
		p = a[i - 2] + p*x;
	}
	cout << p  << endl;
	clock_t end = clock();
	cout << (double)(end - start) / CLK_TCK << endl;
	start = clock();
	int sum = 0;
	for (int i = 0; i < n; i++)
	{
		sum += a[i] * pow(x, i);
	}
	cout << sum << endl;
	end = clock();
	cout << (double)(end - start) / CLK_TCK;
	system("pause");

}