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HDU 5741 Helter Skelter

时间:2016-07-25 00:16:36      阅读:192      评论:0      收藏:0      [点我收藏+]

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离线处理+扫描线。题意很容易转化:若干个矩形形成并集,询问一些点是否在并集中?

官方题解不是这样做的....那种做法效率更高,暂时还不会。我这样是4500ms G++过的,C++TLE......

区间加上某值,询问单点值,可以用树状数组。用线段树可能常数较大导致TLE。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi = acos(-1.0), eps = 1e-8;
void File()
{
    freopen("D:\\in.txt", "r", stdin);
    freopen("D:\\out.txt", "w", stdout);
}
inline int read()
{
    char c = getchar();  while (!isdigit(c)) c = getchar();
    int x = 0;
    while (isdigit(c)) { x = x * 10 + c - 0; c = getchar(); }
    return x;
}

int T, n, ps, pq, v[1010], c[2000000 + 10];
int A[2000000 + 10], sz;
struct Seg { int x, y1, y2, f; }s[2000000 + 10]; int ns;
struct Quary { int x, y, id; }q[500000 + 10]; int nq;
int ans[500000 + 10];

int lowbit(int x) { return x&(-x); }
void add(int p, int val) { while (p <= sz) c[p] = c[p] + val, p = p + lowbit(p); }
int sum(int p) { int r = 0; while (p > 0) r = r + c[p], p = p - lowbit(p); return r; }
void update(int L, int R, int val) { add(L, val); add(R + 1, -val); }

void AddSeg(int l, int r, int L, int R)
{
    s[ns].x = l, s[ns].y1 = L, s[ns].y2 = R, s[ns].f = 1, ns++;
    s[ns].x = r, s[ns].y1 = L, s[ns].y2 = R, s[ns].f = -1, ns++;
    A[sz++] = L, A[sz++] = R;
}

bool cmp(Seg a, Seg b) { if (a.x == b.x) return a.f > b.f; return a.x < b.x; }
bool cmp2(Quary a, Quary b) { return a.x < b.x; }

void get()
{
    int x = lower_bound(A, A + sz, q[pq].y) - A; x++;
    if (sum(x) > 0) ans[q[pq].id] = 1; else ans[q[pq].id] = 0; pq++;
}

void insert()
{
    int L = lower_bound(A, A + sz, s[ps].y1) - A; L++;
    int R = lower_bound(A, A + sz, s[ps].y2) - A; R++;
    update(L, R, s[ps].f); ps++;
}

int main()
{
    scanf("%d", &T); 
    while (T--)
    {
        scanf("%d%d", &n, &nq);
        for (int i = 1; i <= n; i++) scanf("%d", &v[i]);

        ns = 0; sz = 0;
        for (int i = 1; i <= n; i++)
        {
            int l = 0, r = 0, L = 0, R = 0, w = 0, b = 0;
            if (i & 1) AddSeg(0, v[i], 0, 0); else AddSeg(0, 0, 0, v[i]); 
            for (int j = i + 1; j <= n; j++)
            {
                l = r = w; L = R = b;
                if (i & 1) r = r + v[i]; else R = R + v[i];
                if (j & 1) r = r + v[j]; else R = R + v[j];
                AddSeg(l, r, L, R);
                if (j & 1) w = w + v[j]; else b = b + v[j];
            }
        }

        for (int i = 0; i < nq; i++)
        {
            scanf("%d%d", &q[i].x, &q[i].y); q[i].id = i;
            A[sz++] = q[i].y;
        }

        sort(s, s + ns, cmp); sort(q, q + nq, cmp2);
        sort(A, A + sz); sz = unique(A, A + sz) - A;

        ps = 0, pq = 0; memset(c, 0, sizeof c);
        while (pq < nq)
        {
            if (ps == ns) get();
            else
            {
                if (s[ps].x < q[pq].x) insert();
                else if (s[ps].x > q[pq].x) get();
                else { if (s[ps].f == 1) insert(); else get(); }
            }
        }
        for (int i = 0; i < nq; i++) printf("%d", ans[i]); printf("\n");
    }
    return 0;
}

 

HDU 5741 Helter Skelter

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原文地址:http://www.cnblogs.com/zufezzt/p/5701970.html

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