HDU Always Cook Mushroom (极角排序+树状数组)

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2
0 0
3
3 5 8
2 4 7
1 2 3
1 2
3
3 5 8
2 4 7
1 2 3

Case #1:
1842
1708
86
Case #2:
2901
2688
200

思路: 预处理出这1e6个点的极角关系序，离线，将询问也按(a,b)的极角排序。然后只需想象一根表针在逆时针的扫，把扫过的点的权值加到树状数组中，对于每一个询问也仅仅是一个前缀和。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
typedef long long ll;
using namespace std;
const int maxn = 1005;
const int inf = 1e5+5;

struct Point {
	ll a, b;
	double s;
} p[maxn*maxn];
struct Query {
	ll a, b, x, id;
	double s;
} q[maxn*maxn];
ll bit[maxn];
ll ans[inf], Index[inf];
int cnt;

void scan(ll &x) {
	char c;
	while ((c = getchar()) && (c < '0' || c > '9')) ;
	x = c - '0';
	while ((c = getchar()) && (c >= '0' && c <= '9'))
		x = x * 10 + c - '0';
}

void out(ll x) {
	if (x > 9)
		out(x/10);
	putchar(x%10+'0');
}

inline int lowbit(int x) {
	return x & -x;
}

inline void add(int x, int val) {
	while (x <= 1000) {
		bit[x] += val;
		x += lowbit(x);
	}
}

inline ll sum(int x) {
	ll tmp = 0;
	while (x > 0) {
		tmp += bit[x];
		x -= lowbit(x);
	}
	return tmp;
}

bool cmp1(Point x, Point y) {
	return x.s < y.s;
}

bool cmp2(Query x, Query y) {
	if (x.s == y.s)
		return x.x < y.x;
	return x.s < y.s;
}

void init() {
	for (int i = 1; i <= 1000; i++)
		for (int j = 1; j <= 1000; j++) {
			p[cnt].a = i;
			p[cnt].b = j;
			p[cnt++].s = 1.0 * j / i;
		}
	sort(p, p+cnt, cmp1);
}

int main() {
	cnt = 0;
	ll A, B, m;
	init();
	int t, cas = 1;
	scanf("%d", &t);
	while (t--) {
		memset(bit, 0, sizeof(bit));
		scan(A), scan(B), scan(m);
		for (int i = 0; i < m; i++) {
			scan(q[i].a), scan(q[i].b), scan(q[i].x);
			q[i].s = 1.0 * q[i].b / q[i].a;
			q[i].id = i;
		}

		sort(q, q + m, cmp2);
		for (int i = 0; i < m; i++) {
			Index[q[i].id] = i;
		}
		cnt = 0;
		printf("Case #%d:\n", cas++);
		for (int i = 0; i < m; i++) {
			while (p[cnt].s <= q[i].s) {
				add(p[cnt].a, (p[cnt].a+A) * (p[cnt].b + B));
				cnt++;
			}
			ans[i] = sum(q[i].x);
		}
		for (int i = 0; i < m; i++) {
			out(ans[Index[i]]);
			printf("\n");
		}
	}
	return 0;	
}

HDU Always Cook Mushroom (极角排序+树状数组)

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原文地址：http://blog.csdn.net/u011345136/article/details/40631761