[USACO5.3]窗体面积Window Area

https://www.luogu.org/problemnew/show/P2745

上浮法...真是奇特的方法

考虑到我们要把矩形置顶，那么如果我们置顶到第k层，现在摆在我们面前的是第k层的矩形

将矩形分为四个继续上浮即可

#include<cstdio>
#include<iostream>
#include<cstring>
#include<queue>
#include<vector>
#include<map>
#include<climits>
#include<algorithm>
using namespace std;
typedef long long ll;
typedef double db;
#define pii pair<ll,int>
#define mp make_pair
#define B cout << "breakpoint" << endl;
#define O(x) cout << #x << "  " << x << endl;
inline int read()
{
    int ans = 0,op = 1;
    char ch = getchar();
    while(ch < '0' || ch > '9')
    {
        if(ch == '-') op = -1;
        ch = getchar();
    }
    while(ch >= '0' && ch <= '9')
    {
        (ans *= 10) += ch - '0';
        ch = getchar();
    }
    return ans * op;
}
db ans,base;
const int maxn = 1005;
struct node
{
    int x1,y1,x2,y2;
    char id;
    void init() { x1 = y1 = x2 = y2 = 0; id = 0; }
    bool operator == (const node& b) const
    {
        return id == b.id;
    }
}a[maxn],tp[maxn];
bool vis[maxn];
int n;
inline int find(node x) 
{    
    for(int i = 1;i <= n;i++) if(a[i] == x) return i;
}
void move(node x,int f)
{
    int pos = find(x);
    if(f == 0) for(int i = pos;i >= 2;i--) swap(a[i],a[i - 1]);
    else for(int i = pos;i < n;i++) swap(a[i],a[i + 1]);
}
void del(node x)
{
    int pos = find(x);
    tp[x.id] = (node){0,0,0,0,0}; vis[x.id] = 0;
    for(int i = pos + 1;i <= n;i++) a[i - 1] = a[i];
    n--;
}
void dfs(int k,int x1,int y1,int x2,int y2)
{
    if(x1 == x2 || y1 == y2) return;
    if(k == 0) { ans += (db)(x2 - x1) * (y2 - y1); return; }
    int a1 = a[k].x1,b1 = a[k].y1,a2 = a[k].x2,b2 = a[k].y2;
    if(x1 > a2 || x2 < a1 || y1 > b2 || y2 < b1)
        { dfs(k - 1,x1,y1,x2,y2); return; }
    if(a1 <= x1 && a2 >= x2  && b1 <= y1 && b2 >= y2) return;
    dfs(k - 1,x1,min(y2,b2),min(x2,a2),y2);
    dfs(k - 1,min(a2,x2),max(y1,b1),x2,y2);
    dfs(k - 1,max(x1,a1),y1,x2,max(y1,b1));
    dfs(k - 1,x1,y1,max(x1,a1),min(y2,b2));
}
int main()
{
    char op;
    int x1,y1,x2,y2;
    char id;
    node tpt;
    while(cin >> op)
    {
        if(op == 's')
        {
            scanf("(%c",&id);
            int pos = 0;
            for(int i = 1;i <= n;i++) if(a[i] == tp[id]) pos = i;
            ans = 0,base = (db)(a[pos].x2 - a[pos].x1) * (a[pos].y2 - a[pos].y1);
            dfs(pos - 1,a[pos].x1,a[pos].y1,a[pos].x2,a[pos].y2);
            printf("%.3lf
",ans * 100 / base);
        }
        else
        {
            scanf("(%c,%d,%d,%d,%d)", &id, &x1, &y1, &x2, &y2);
            if(x1 > x2) swap(x1, x2); if(y1 > y2) swap(y1, y2);
            tpt = (node){x1,y1,x2,y2,id};
            if(op == 'w')
            {
                if(vis[id]) continue;
                tp[id] = a[++n] = tpt,move(tpt,0),vis[id] = 1;
            }
            if(op == 't') move(tpt, 0);
            if(op == 'b') move(tpt, 1);
            if(op == 'd') del(tpt); 
        }
    }
}