hdu 1828 Picture(扫描线)

hdu 1828 Picture(扫描线)

题意：算多个矩形的周长并。

线段树，扫描线。。

#include<stdio.h>#include<string.h>#include<stdlib.h>#include<algorithm>#define ll __int64#define lson l , m , rt << 1#define rson m + 1 , r , rt << 1 | 1using namespace std ;int max ( int a , int b ) { return a > b ? a : b ; }int min ( int a , int b ) { return a < b ? a : b ; }const int maxn = 222222 ;int sum[maxn<<2] , cnt[maxn<<2] ;struct Edge{    int l , r , h , id ;    bool operator < ( const Edge &p ) const    {        return h < p.h ;    }}edge[maxn] ;struct Rec{    int a , b , c , d ;} rec[maxn] ;void init (){    memset ( sum , 0 , sizeof ( sum ) ) ;    memset ( cnt , 0 , sizeof ( cnt ) ) ;}void build_seg ( int l , int r , int h , int id , int i ){    edge[i].l = l , edge[i].r = r , edge[i].h = h , edge[i].id = id ;}void push_up ( int l , int r , int rt ){    if ( cnt[rt] ) sum[rt] = r - l + 1 ;    else if ( l == r ) sum[rt] = 0 ;    else sum[rt] = sum[rt<<1] + sum[rt<<1|1] ;}void update ( int a , int b , int c , int l , int r , int rt ){    if ( a <= l && r <= b )    {        cnt[rt] += c ;        push_up ( l , r , rt ) ;        return ;    }    int m = ( l + r ) >> 1 ;    ll ret = 0 ;    if ( a <= m ) update ( a , b , c , lson ) ;    if ( m < b ) update ( a , b , c , rson ) ;    push_up ( l , r , rt ) ;}ll solve ( int m ){    init () ;    ll ret = 0 ;    sort ( edge + 1 , edge + m + 1 ) ;    int i , last = 0 ;    int l = 10001 , r = -10001 ;    for ( i = 1 ; i <= m ; i ++ )     {        r = max ( r , edge[i].r ) ;        l = min ( l , edge[i].l ) ;    }    for ( i = 1 ; i <= m ; i ++ )    {        update ( edge[i].l , edge[i].r - 1 , edge[i].id , l , r , 1 ) ;        ret += abs ( last - sum[1] ) ;        last = sum[1] ;    }    return ret ;}int main (){    int n , i , j , a , b , c , d ;    while ( scanf ( "%d" , &n ) != EOF )    {        ll ans = 0 ;        for ( i = 1 ; i <= n ; i ++ )            scanf ( "%d%d%d%d" , &rec[i].a , &rec[i].b , &rec[i].c , &rec[i].d ) ;        int m = 0 ;        for ( i = 1 ; i <= n ; i ++ )        {            m ++ ;            build_seg ( rec[i].a , rec[i].c , rec[i].b , 1 , m ) ;            m ++ ;            build_seg ( rec[i].a , rec[i].c , rec[i].d , -1 , m ) ;        }        ans += solve ( m ) ;        m = 0 ;        for ( i = 1 ; i <= n ; i ++ )        {            m ++ ;            build_seg ( rec[i].b , rec[i].d , rec[i].a , 1 , m ) ;            m ++ ;            build_seg ( rec[i].b , rec[i].d , rec[i].c , -1 , m ) ;        }        ans += solve ( m ) ;        printf ( "%I64d\n" , ans ) ;    }}