【洛谷】P1023 税收与补贴问题 （题解）

P1023 税收与补贴问题

---

题解：

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int s, a, b, d, n = 0;
int a1, a2, a3, b1, b2, b3;
bool judge(int x)
{
	int c1 = (a1 - a + x) * b1;
	int c2 = (a2 - a + x) * b2;
	int c3 = (a3 - a + x) * b3;
	if (c2 >= c1&& c2 >= c3)
	{
		return 1;
	}
	else
	{
		return 0;
	}
}
int main()
{
	bool temp = 1;
	cin >> s;
	cin >> a >> b;
	int i;
	a1 = s - 1;
	a2 = s;
	a3 = s + 1;
	int p1 = a, p2 = b;
	for (i = 0; 1; i++)
	{
		int temp1, temp2;
		cin >> temp1 >> temp2;
		if (temp1 == -1 && temp2 == -1)
		{
			break;
		}
		if (temp1 == a1)
		{
			b1 = temp2;
		}
		else if (temp1 > a1&& a1 > p1)
		{
			b1 = p2+(temp2 - p2) / (temp1 - p1) * (a1-p1);
		}
		if (temp1 == a2)
		{
			b2 = temp2;
		}
		else if (temp1 > a2&& a2 > p1)
		{
			b2= p2+(temp2 - p2) / (temp1 - p1) * (a2-p1);
		}
		if (temp1 == a3)
		{
			b3 = temp2;
		}
		else if (temp1 > a3&& a3 > p1)
		{
			b3 = p2+(temp2 - p2) / (temp1 - p1) * (a3-p1);
		}
		n++;
		p1 = temp1;
		p2 = temp2;
	}
	cin >> d;
	if (a1 > p1)
	{
		b1 = p2 - (a1 - p1) * d;
	}
	if (a2 > p1)
	{
		b2 = p2 - (a2 - p1) * d;
	}
	if (a3 > p1)
	{
		b3 = p2 - (a3 - p1) * d;
	}
	for (int i = 0; i < 10000; i++)
	{
		if (judge(i))
		{
			cout << i << endl;
			return 0;
		}
		if (judge(-i))
		{
			cout << -i << endl;
			return 0;
		}
	}
	cout << "NO SOLUTION" << endl;
	return 0;
}