HDU 1828 Picture

线段树矩形周长并

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>

#define lson l, m, rt << 1
#define rson m + 1, r, rt << 1 | 1

using namespace std;

struct Seg_Tree
{
    int l, r, h, s;
    Seg_Tree() {}
    Seg_Tree( int a, int b, int c, int d ):l(a), r(b), h(c), s(d) { }
    bool operator<( const Seg_Tree &rhs ) const
    {
        if ( h == rhs.h ) return s > rhs.s;
        return h < rhs.h;
    }
};

const int MAXN = 5004 << 2;
const int INF = 1 << 30;

Seg_Tree R[MAXN];
int cnt[MAXN << 2 ];
int segnum[MAXN << 2];
int len[MAXN << 2];
bool lbd[MAXN << 2], rbd[MAXN << 2];

void PushUp( int rt, int l, int r )
{
    int lc = rt << 1;
    int rc = rt << 1 | 1;
    if ( cnt[rt] )
    {
        lbd[rt] = rbd[rt] = true;
        len[rt] = r - l + 1;
        segnum[rt] = 2;
    }
    else if ( l == r )
    {
        len[rt] = segnum[rt] = 0;
        lbd[rt] = rbd[rt] = false;
    }
    else
    {
        lbd[rt] = lbd[lc];
        rbd[rt] = rbd[rc];
        len[rt] = len[lc] + len[rc];
        segnum[rt] = segnum[lc] + segnum[rc];
        if ( rbd[lc] && lbd[rc] ) segnum[rt] -= 2;
    }
    return;
}

void Update( int L, int R, int c, int l, int r, int rt )
{
    if ( L <= l && r <= R )
    {
        cnt[rt] += c;
        PushUp( rt, l, r );
        return;
    }

    int m = ( l + r ) >> 1;
    if ( L <= m ) Update( L, R, c, lson );
    if ( R > m ) Update( L, R, c, rson );
    PushUp( rt, l, r );
    return;
}

int main()
{
    int N;
    while ( ~scanf( "%d", &N ) )
    {
        int m = 0;
        int low = INF, high = -INF;
        for ( int i = 0; i < N; ++i )
        {
            int a, b, c, d;
            scanf( "%d%d%d%d", &a, &b, &c, &d );
            low = min( low, a );
            high = max( high, c );
            R[ m++ ] = Seg_Tree( a, c, b, 1 );
            R[ m++ ] = Seg_Tree( a, c, d, -1 );
        }

        sort( R, R + m );

        int ans = 0, last = 0;
        for ( int i = 0; i < m; ++i )
        {
            if ( R[i].l < R[i].r ) Update( R[i].l, R[i].r - 1, R[i].s, low, high - 1, 1 );
            ans += segnum[1] * ( R[i + 1].h - R[i].h );
            ans += abs( len[1] - last );
            last = len[1];
        }
        printf( "%d\n", ans );
    }
    return 0;
}