POJ 1389 (扫描线)

来源：互联网发布：江阴市网络教研平台编辑：程序博客网时间：2024/05/16 05:33
第一题扫描线，连离散化都不用0.0
#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <iostream>using namespace std;#define maxn 51111#define pl c<<1#define pr (c<<1)|1#define lson tree[c].l,tree[c].mid,c<<1#define rson tree[c].mid+1,tree[c].r,(c<<1)|1struct node {    int l, r, mid;    int len;    int cover;}tree[maxn<<4];struct segment {    int l, r, h, flag;    bool operator < (segment a) const {        return h < a.h;    }}p[2222];void build_tree (int l, int r, int c) { //cout << l << " " << r << endl;    tree[c].l = l, tree[c].r = r, tree[c].mid = (l+r)>>1;    tree[c].len = 0, tree[c].cover = 0;    if (l == r)        return ;    build_tree (lson);    build_tree (rson);    return ;}void push_up (int c) {    if (tree[c].cover) {        tree[c].len = (tree[c].r - tree[c].l+1);    }    else {        tree[c].len = tree[pl].len + tree[pr].len;    }}void update (int l, int r, int c, int x, int y, int v) {    if (x == l && y == r) {        tree[c].cover += v;        push_up (c);        return ;    }    if (tree[c].mid >= y)        update (lson, x, y, v);    else if (tree[c].mid < x)        update (rson, x, y, v);    else {        update (lson, x, tree[c].mid, v);        update (rson, tree[c].mid+1, y, v);    }    push_up (c);}int a, b, c, d;int cnt;void add () {    c--;    p[cnt].l = a, p[cnt].r = c, p[cnt].h = b, p[cnt].flag = 1;    cnt++;    p[cnt].l = a, p[cnt].r = c, p[cnt].h = d, p[cnt].flag = -1;    cnt++;}int main () {    //freopen ("in", "r", stdin);    while (scanf ("%d%d%d%d", &a, &b, &c, &d) == 4 && a+b+c+d != -4) {        cnt = 0;        add ();        while (scanf ("%d%d%d%d", &a, &b, &c, &d) == 4 && a+b+c+d != -4) {            add ();        }        sort (p, p+cnt);        build_tree (0, 50000, 1);        long long ans = 0;        for (int i = 0; i < cnt-1; i++) {            update (0, 50000, 1, p[i].l, p[i].r, p[i].flag);            ans += (p[i+1].h - p[i].h) * (long long)tree[1].len;        }        printf ("%lld\n", ans);    }    return 0;}
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