AcWing 5525. 炮弹 纯模拟的简单题

5525. 炮弹 - AcWing题库

注意判掉死循环即可

const int N = 1e5 + 10;
int n,m;

struct Node
{
	int q,v;
	bool error;//1被击破，0未被击破
}a[N];


void solve()
{
	cin >> n >> m;
	for (int i = 1;i <= n; i++)
	{
		int q,v; cin >> q >> v;
		a[i] = {q,v};
	}
	
	LL cnt = 0;
	LL len = 1;//步长
	int fx = 1;//右为1,左为-1
	
	if (a[m].q == 1 && len >= a[m].v) cnt ++,a[m].error = true;//被击毁
	if (a[m].q == 0) len += a[m].v,fx = -fx;
	
	m = m + fx*len;
	
	LL sum = 0;
	
	while(m >= 1 && m <= n)
	{
		if (sum >= 1e6) break;//防止死循环
		sum ++;	
		
		if (a[m].q == 1)
		{
			if (len >= a[m].v && !a[m].error) cnt++,a[m].error = true;
			m = m + fx*len;
		}
		else
		{
			len += a[m].v,fx = -fx;
			m = m + fx*len;
		}
	}
	cout << cnt << endl;
}