BZOJ1227或洛谷2154 [SDOI2009]虔诚的墓主人

BZOJ原题链接

洛谷原题链接

又是扫描线，题解可看大佬的博客（太懒了不想打）

#include<cstdio>
#include<algorithm>
using namespace std;
const int N = 1e5 + 10;
const long long mod = 2147483648LL;
struct dd {
	int x, y;
};
dd a[N];
int ls_x[N], ls_y[N], sx[N], sy[N], S[N], C[N][12], nwy[N], la[N], xl, yl;
inline int re()
{
	int x = 0;
	char c = getchar();
	bool p = 0;
	for (; c < '0' || c > '9'; c = getchar())
		p |= c == '-';
	for (; c >= '0' && c <= '9'; c = getchar())
		x = x * 10 + c - '0';
	return p ? -x : x;
}
inline int MOD(long long x)
{
	if (x < mod)
		return x;
	return x % mod;
}
inline int lowbit(int x) { return x & -x; }
inline void add(int x, int y)
{
	for (; x <= yl; x += lowbit(x))
		S[x] = MOD(1LL * S[x] + y);
}
inline int ask(int x)
{
	int s = 0;
	for (; x; x -= lowbit(x))
		s = MOD(1LL * s + S[x]);
	return s;
}
bool comp(dd x, dd y)
{
	if (!(x.x ^ y.x))
		return x.y < y.y;
	return x.x < y.x;
}
inline int minn(int x, int y) { return x < y ? x : y; }
inline int BSX(int x)
{
	int l = 1, r = xl, mid;
	while (l <= r)
	{
		mid = (l + r) >> 1;
		if (!(ls_x[mid] ^ x))
			return mid;
		ls_x[mid] > x ? r = mid - 1 : l = mid + 1;
	}
	return 0;
}
inline int BSY(int x)
{
	int l = 1, r = yl, mid;
	while (l <= r)
	{
		mid = (l + r) >> 1;
		if (!(ls_y[mid] ^ x))
			return mid;
		ls_y[mid] > x ? r = mid - 1 : l = mid + 1;
	}
	return 0;
}
int main()
{
	int i, j, n, m, s, o, v, an = 0;
	re(); re();
	n = re();
	for (i = 1; i <= n; i++)
	{
		ls_x[i] = a[i].x = re() + 1;
		ls_y[i] = a[i].y = re() + 1;
	}
	m = re();
	sort(ls_x + 1, ls_x + n + 1);
	sort(ls_y + 1, ls_y + n + 1);
	ls_x[n + 1] = ls_y[n + 1] = -1;
	for (i = 1; i <= n; i++)
		if (ls_x[i] ^ ls_x[i + 1])
			ls_x[++xl] = ls_x[i];
	for (i = 1; i <= n; i++)
		if (ls_y[i] ^ ls_y[i + 1])
			ls_y[++yl] = ls_y[i];
	for (i = 1; i <= n; i++)
	{
		a[i].x = BSX(a[i].x);
		a[i].y = BSY(a[i].y);
		sx[a[i].x]++;
		sy[a[i].y]++;
	}
	sort(a + 1, a + n + 1, comp);
	for (C[0][0] = 1, i = 1; i <= n; i++)
		for (j = C[i][0] = 1, o = minn(i, m); j <= o; j++)
			C[i][j] = C[i - 1][j] + C[i - 1][j - 1];
	for (i = 1; i <= n; i++)
	{
		if (a[i].x ^ a[i - 1].x)
			s = 0;
		else
		{
			s++;
			an = MOD(an + MOD(1LL * MOD(1LL * ask(a[i].y - 1) - ask(a[i - 1].y)) * MOD(1LL * C[s][m] * C[sx[a[i].x] - s][m])));
		}
		nwy[o = a[i].y]++;
		v = MOD(1LL * C[nwy[o]][m] * C[sy[o] - nwy[o]][m]);
		add(o, v - la[o]);
		la[o] = v;
	}
	printf("%lld", (1LL * an + mod) % mod);
	return 0;
}