HDU

线段树扫描线, 离散化

写成notonlysuccess风格爽多了…

#include <iostream>#include <algorithm>#include <cstdio>#include <cstring>#define ls l, m, rt<<1#define rs m+1, r, rt<<1|1#define defm int m = (l+r)>>1using namespace std;const int MAXN = 105;int n, cover[MAXN<<3];double x1, x2, y1, y2, x[MAXN<<1], len[MAXN<<3];struct Seg{    double l, r, h;    int f;    Seg(double ll = 0, double rr = 0, double hh = 0, int ff = 0)        :l(ll), r(rr), h(hh), f(ff) {}    operator<(Seg a) { return h < a.h; }};Seg seg[MAXN<<1];void build(int l, int r, int rt){    cover[rt] = 0;    len[rt] = 0;    if(l == r) return;    defm;    build(ls);    build(rs);}void pushUp(int l, int r, int rt){    if(cover[rt]) len[rt] = x[r+1] - x[l];    else if(l==r) len[rt] = 0;    else len[rt] = len[rt<<1] + len[rt<<1|1];}void update(int L, int R, int v, int l, int r, int rt){    if(L <= l && r <= R)    {        cover[rt] += v;        pushUp(l, r, rt);        return;    }    if(L > r || l > R) return;    defm;    update(L, R, v, ls);    update(L, R, v, rs);    pushUp(l, r, rt);}int main(){    int cas = 1;    while(scanf("%d", &n) == 1 && n)    {        int cnt = 0;        for(int i=0; i<n; ++i)        {            scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);            seg[cnt] = Seg(x1, x2, y1, 1);            x[cnt++] = x1;            seg[cnt] = Seg(x1, x2, y2, -1);            x[cnt++] = x2;        }        sort(seg, seg+cnt);        sort(x, x+cnt);        int m = unique(x, x+cnt) - x;        build(0, m-1, 1);        double ans = 0;        int l, r;        for(int i=0; i<cnt; ++i)        {            l = lower_bound(x, x+m, seg[i].l) - x;            r = lower_bound(x, x+m, seg[i].r) - x - 1;            update(l, r, seg[i].f, 0, m-1, 1);            ans += (seg[i+1].h - seg[i].h) * len[1];        }        printf("Test case #%d\n", cas++);        printf("Total explored area: %.2f\n\n",ans);    }    return 0;}

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