【HDU】1828-Picture(线段树扫描线）

矩阵交并周长的模板题

这题不需要离散化，需要注意的时候负坐标转化成正坐标

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define lson (pos<<1)
#define rson (pos<<1|1)
typedef long long LL;
const int maxn = 30005;
const int ADD  = 10001;
struct Seg{
    int l,r,c,h;
    Seg(int l = 0,int r = 0,int h = 0,int c = 0):l(l),r(r),h(h),c(c){};
    friend bool operator < (Seg p,Seg q){
        return p.h < q.h;
    }
}seg[maxn];
struct Node{
    int l,r,cover,sum1,sum2;
    bool left,right;
    int mid(){
        return (l + r) >> 1;
    }
    int len(){
        return  r - l + 1;
    }
}node[maxn << 2];
int cnt;
void build(int l,int r,int pos){
    node[pos].l = l; node[pos].r = r;
    node[pos].sum1 = node[pos].sum2 = 0;
    node[pos].left = node[pos].right = false;
    node[pos].cover = 0;
    if(l == r) return;
    int mid = (l + r) >> 1;
    build(l,mid,lson);
    build(mid + 1,r,rson);
}
void pushup(int pos){
    if(node[pos].cover){
        node[pos].sum1 = 2;
        node[pos].sum2 = node[pos].len();
        node[pos].left = node[pos].right = true;
    }
    else if(node[pos].len() == 1){
        node[pos].sum1 = node[pos].sum2 = node[pos].left = node[pos].right = 0;
    }
    else{
        node[pos].sum1  = node[lson].sum1 + node[rson].sum1;
        if(node[lson].right && node[rson].left) node[pos].sum1 -= 2;
        node[pos].sum2  = node[lson].sum2 + node[rson].sum2;
        node[pos].left  = node[lson].left;
        node[pos].right = node[rson].right;
    }
}
void update(int l,int r,int pos,int d){
    if(l <= node[pos].l && node[pos].r <= r){
        node[pos].cover += d;
        pushup(pos);
        return;
    }
    int mid = node[pos].mid();
    if(l <= mid)
        update(l,r,lson,d);
    if(r  > mid)
        update(l,r,rson,d);
    pushup(pos);
    return;
}
int main(){
    int n;
    while(scanf("%d",&n) != EOF){
        build(1,30000,1);
        cnt = 0;
        for(int i = 0; i < n; i++){
            int a,b,c,d;
            scanf("%d%d%d%d",&a,&b,&c,&d);
            a += ADD; c += ADD;
            seg[cnt++] = Seg(a,c,d,1);
            seg[cnt++] = Seg(a,c,b,-1);
        }
        sort(seg,seg + cnt);
        LL ans = 0,last = 0;
        for(int i = 0; i < cnt; i++){
            int l = seg[i].l,r = seg[i].r,c = seg[i].c;
            update(l,r - 1,1,c);
            if(i < cnt - 1)
                ans += node[1].sum1 * (seg[i + 1].h - seg[i].h);
            ans += abs(node[1].sum2 - last);
            last = node[1].sum2;
        }
        printf("%I64d\n",ans);
    }
    return 0;
}