【BZOJ 1018】 [SHOI2008]堵塞的交通traffic

【题目链接】:http://www.lydsy.com/JudgeOnline/problem.php?id=1018

【题意】

【题解】



按照这里的题解写的http://blog.csdn.net/popoqqq/article/details/44116729

主要思路就是根据最小单元的合并方式推出整个线段的合并.

其中要往左走和往右走的过程,可以一开始让那个点往左移动,看看最远能到哪里,右边的点也一样,一直向右移动看看最远能到哪;

然后在最左和最右之间求联通性;

a[x][y]表示这个区间的左端点的上下方和右端点的上下方的连通性;

可以根据这个合并区间;

线段树操作特别是往最左找的过程不好写;



【完整代码】

#include <bits/stdc++.h>
using namespace std;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define LL long long
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep2(i,a,b) for (int i = a;i >= b;i--)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define rei(x) scanf("%d",&x)
#define rel(x) scanf("%lld",&x)

typedef pair<int, int> pii;
typedef pair<LL, LL> pll;

const int dx[9] = { 0,1,-1,0,0,-1,-1,1,1 };
const int dy[9] = { 0,0,0,-1,1,-1,1,-1,1 };
const double pi = acos(-1.0);
const int N = 110;
const int M = 1e5 + 100;

int n;
bool a[M][2];

struct abcd
{
    bool a[2][2];
    abcd(bool _ = false)
    {
        a[0][0] = a[1][1] = true;
        a[0][1] = a[1][0] = _;
    }
    bool* operator [] (int x)
    {
        return a[x];
    }
    friend abcd merge(bool sta[2], abcd x, abcd y)
    {
        abcd re;
        re[0][0] = (x[0][0] & sta[0] & y[0][0]) | (x[0][1] & sta[1] & y[1][0]);
        re[1][1] = (x[1][1] & sta[1] & y[1][1]) | (x[1][0] & sta[0] & y[0][1]);
        re[0][1] = (x[0][0] & sta[0] & y[0][1]) | (x[0][1] & sta[1] & y[1][1]);
        re[1][0] = (x[1][0] & sta[0] & y[0][0]) | (x[1][1] & sta[1] & y[1][0]);
        return re;
    }
};

struct segtree
{
    segtree *ls, *rs;
    abcd status;
    segtree() :ls(0x0), rs(0x0) {}
#define push_up(); status = merge(a[mid],ls->status,rs->status);
    void Build_Tree(int x, int y)
    {
        if (x == y) return;
        int mid = (x + y) >> 1;
        ls = new segtree, rs = new segtree;
        ls->Build_Tree(x, mid);
        rs->Build_Tree(mid + 1, y);
        push_up();
    }
    void refresh(int x, int y, int pos)
    {
        int mid = (x + y) >> 1;
        if (pos == mid)
        {
            push_up();
            return;
        }
        if (pos < mid)
            ls->refresh(x, mid, pos);
        else
            rs->refresh(mid + 1, y, pos);
        push_up();
    }
    void modify(int x, int y, int pos, int flag)
    {
        int mid = (x + y) >> 1;
        if (x == y)
        {
            new(&status) abcd(flag);
            return;
        }
        if (pos <= mid)
            ls->modify(x, mid, pos, flag);
        else
            rs->modify(mid + 1, y, pos, flag);
        push_up();
    }
    void _get_left(int x, int y, int &pos, abcd &sta, int flag)
    {
        int mid = (x + y) >> 1;
        if (x == y) return;
        abcd temp = merge(a[y], rs->status, sta);
        if (temp[0][flag] || temp[1][flag])
            pos = mid + 1, sta = temp, ls->_get_left(x, mid, pos, sta, flag);
        else
            rs->_get_left(mid + 1, y, pos, sta, flag);
    }
    void get_left(int x, int y, int &pos, abcd &sta, int flag)
    {
        if (x == y) return;
        int mid = (x + y) >> 1;
        if (pos <= mid)
            ls->get_left(x, mid, pos, sta, flag);
        else
        {
            //pos > mid
            rs->get_left(mid + 1, y, pos, sta, flag);
            if (pos != mid + 1) return;
            //pos==mid+1;
            abcd temp = merge(a[mid], ls->status, sta);
            if (temp[0][flag] || temp[1][flag])
                pos = x, sta = temp;
            else
                ls->_get_left(x, mid, pos, sta, flag);
        }
    }
    void _get_right(int x, int y, int &pos, abcd &sta, int flag)
    {
        int mid = (x + y) >> 1;
        if (x == y) return;
        abcd temp = merge(a[x - 1], sta, ls->status);
        if (temp[flag][0] || temp[flag][1])
            pos = mid, sta = temp, rs->_get_right(mid + 1, y, pos, sta, flag);
        else
            ls->_get_right(x, mid, pos, sta, flag);
    }
    void get_right(int x, int y, int &pos, abcd &sta, int flag)
    {
        if (x == y) return;
        int mid = (x + y) >> 1;
        if (mid < pos)
            rs->get_right(mid + 1, y, pos, sta, flag);
        else
        {
            //pos <= mid
            ls->get_right(x, mid, pos, sta, flag);
            if (pos != mid) return;
            //pos==mid
            abcd temp = merge(a[mid], sta, rs->status);
            if (temp[flag][0] || temp[flag][1])
                pos = y, sta = temp;
            else
                rs->_get_right(mid + 1, y, pos, sta, flag);
        }
    }
    abcd get_ans(int x, int y, int l, int r)
    {
        if (x == l && y == r)
            return status;
        int mid = (x + y) >> 1;
        if (mid < l)
            return rs->get_ans(mid + 1, y, l, r);
        if (r <= mid)
            return ls->get_ans(x, mid, l, r);
        return merge(a[mid], ls->get_ans(x, mid, l, mid), rs->get_ans(mid + 1, y, mid + 1, r));
    }
} *tree = new segtree;

void modify(int x1, int y1, int x2, int y2, bool flag)
{
    if (x1 == x2)
    {
        if (y1 > y2) swap(y1, y2);
        a[y1][x1 - 1] = flag;
        tree->refresh(1, n, y1);
        return;
    }
    //y1 == y2
    tree->modify(1, n, y1, flag);
}

void query(int x1, int y1, int x2, int y2)
{
    if (y1 > y2)
    {
        swap(x1, x2);
        swap(y1, y2);
    }
    abcd temp(false);
    tree->get_left(1, n, y1, temp, x1 - 1);
    x1 = temp[0][x1 - 1] ? 1 : 2;

    abcd temp1(false);
    tree->get_right(1, n, y2, temp1, x2 - 1);
    x2 = temp1[x2 - 1][0] ? 1 : 2;

    abcd temp2 = tree->get_ans(1, n, y1, y2);
    puts(temp2[x1 - 1][x2 - 1] ? "Y" : "N");
}

int main()
{
    //freopen("F:\\rush.txt", "r", stdin);
    rei(n);
    tree->Build_Tree(1, n);
    int x1, y1, x2, y2;
    char p[10];
    while (1)
    {
        scanf("%s", p);
        rei(x1), rei(y1), rei(x2), rei(y2);
        if (p[0] == 'C')
            modify(x1, y1, x2, y2, false);
        if (p[0] == 'O')
            modify(x1, y1, x2, y2, true);
        if (p[0] == 'A')
            query(x1, y1, x2, y2);
        if (p[0] == 'E')
            break;
    }
    return 0;
}