树状数组求逆序和模板

C++ code:

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#define lowbit(i) (i & -i);

using namespace std;

struct lines
{
	long l, r, i;
}line[30001];
bool cmp_1(lines, lines);
bool cmp_2(lines, lines);

int main()
{
	long A, B, n, i, k, b, T[30001], m, j;

	while(scanf("%ld%ld", &A, &B) == 2)
	{
		scanf("%ld", &n);
		for(i = 1; i <= n; i++)
		{
			scanf("%ld%ld", &k, &b);
			line[i].l = k * A + b;
			line[i].r = k * B + b;
			T[i] = lowbit(i);
		}
		sort(line + 1, line + n + 1, cmp_1);
		for(i = 1; i <= n; i++)
			line[i].i = i;
		sort(line + 1, line + n + 1, cmp_2);
		T[0] = m = 0;
		for(i = 1; i <= n; i++)
		{
			j = line[i].i - 1;
			while(j)
			{
				m += T[j];
				j -= lowbit(j);
			}
			j = line[i].i;
			while(j <= n)
			{
				T[j]--;
				j += lowbit(j);
			}
		}
		printf("%ld\n", n + m + 1);
	}

	return 0;
}

bool cmp_1(lines a, lines b)
{
	return a.l > b.l;
}

bool cmp_2(lines a, lines b)
{
	return a.r > b.r;
}