poj3334Connected Gheeves(二分）

链接

二分高度，算面积的地方有点麻烦，没有用求交点的模板，直接自己按三角形相似手算了一下，写的有点麻烦。

上下界直接取水可放的最高点以及最低点。

自己的长得很挫的代码

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
using namespace std;
#define N 2010
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
struct point
{
    double x ,y;
    point(double x=0,double y=0):x(x),y(y){}
}p[N],q[N],ch[N];
double minz;
int n,m;
typedef point pointt;
pointt operator -(point a,point b)
{
    return point(a.x-b.x,a.y-b.y);
}
int dcmp(double x)
{
    if(fabs(x)<eps) return 0;
    return x<0?-1:1;
}
double dis(point a)
{
    return sqrt(a.x*a.x+a.y*a.y);
}
double cross(point a,point b)
{
    return a.x*b.y-a.y*b.x;
}
double getarea(int n,point p[])
{
    int i;
    double s = 0;
    for(i = 2; i < n ; i++)
    s+=cross(p[i]-p[1],p[i+1]-p[1]);
    return s/2;
}
double cal(double r,point p[],int n)
{
    int i,j;
    int k = 1;
    for(i = 1; i <= n; i++)
    if(p[i].y<p[k].y)    k = i;

    if(dcmp(r-p[k].y)<=0) return 0.0;

    point p1,p2;
    int g = 0;
    for(i = 1; i < k; i++)
    if(dcmp(p[i].y-r)>=0&&dcmp(p[i+1].y-r)<0)
    {
        p1.y = r;
        double d = r-p[i+1].y;
        p1.x = d*(p[i].x-p[i+1].x)/(p[i].y-p[i+1].y)+p[i+1].x;
        break;
    }

    for(j = k ; j >= i+1; j--)
    ch[++g] = p[j];
    ch[++g] = p1;
    for(i = k+1 ; i <= n; i++)
    if(dcmp(p[i-1].y-r)<0&&dcmp(p[i].y-r)>=0)
    {
        p2.y = r;
        double d = r-p[i-1].y;
        p2.x = d*(p[i].x-p[i-1].x)/(p[i].y-p[i-1].y)+p[i-1].x;
        break;
    }
    ch[++g] = p2;
    for(j = i-1 ; j > k; j--)
    ch[++g] = p[j];

    return fabs(getarea(g,ch));
}
int main()
{
    int t,i,a;
    cin>>t;
    while(t--)
    {
        scanf("%d",&a);
        scanf("%d",&n);
        minz = INF;
        double maxz  = INF;
        for(i = 1; i <= n ;i++)
        {
            scanf("%lf%lf",&p[i].x,&p[i].y);
            maxz = min(maxz,p[i].y);
        }
        scanf("%d",&m);
        for(i = 1; i <= m ;i++)
        {
            scanf("%lf%lf",&q[i].x,&q[i].y);
            maxz = min(maxz,p[i].y);
        }
        minz = min(min(p[1].y,p[n].y),min(q[1].y,q[m].y));
        double lef = maxz,rig = minz,mid;
        while(fabs(rig-lef)>eps)
        {
            mid = (rig+lef)/2.0;
            double s1 = cal(mid,p,n),s2 = cal(mid,q,m);
            if(dcmp(s1+s2-a)>0)
            rig = mid;
            else lef = mid;
        }
        printf("%.3f
",lef);
    }
    return 0;
}

感觉不错的别人的代码

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<vector>
#include<cmath>
#include<queue>
#include<set>
using namespace std;
#define N 2010
#define LL long long
#define INF 0xfffffff
const double eps = 1e-8;
const double pi = acos(-1.0);
const double inf = ~0u>>2;
struct point
{
    double x ,y;
    point(double x=0,double y=0):x(x),y(y){}
}p[N],q[N],ch[N];
double minz;
typedef point pointt;
pointt operator -(point a,point b)
{
    return point(a.x-b.x,a.y-b.y);
}
int dcmp(double x)
{
    if(fabs(x)<eps) return 0;
    return x<0?-1:1;
}
double dis(point a)
{
    return sqrt(a.x*a.x+a.y*a.y);
}
double cross(point a,point b)
{
    return a.x*b.y-a.y*b.x;
}

double getarea(int n,point p[])
{
    int i;
    double s = 0;
    for(i = 1; i < n-1 ; i++)
    s+=cross(p[i]-p[0],p[i+1]-p[0]);
    return s/2;
}
//double cal(double r,point p[],int n)
//{
//    int i,j;
//    int k = 1;
//    for(i = 1; i <= n; i++)
//    if(p[i].y<p[k].y)    k = i;
//
//    r = min(r,minz);
//    if(dcmp(r-p[k].y)<=0) return 0.0;
//
//    point p1,p2;
//    int g = 0;
//    for(i = 1; i < k; i++)
//    if(dcmp(p[i].y-r)>=0&&dcmp(p[i+1].y-r)<0)
//    {
//        p1.y = r;
//        double d = r-p[i+1].y;
//        p1.x = d*(p[i].x-p[i+1].x)/(p[i].y-p[i+1].y)+p[i+1].x;
//        break;
//    }
//   // cout<<p1.x<<" "<<p1.y<<endl;
//    for(j = k ; j >= i+1; j--)
//    ch[++g] = p[j];
//    ch[++g] = p1;
//    for(i = k+1 ; i <= n; i++)
//    if(dcmp(p[i-1].y-r)<0&&dcmp(p[i].y-r)>=0)
//    {
//        p2.y = r;
//        double d = r-p[i-1].y;
//        p2.x = d*(p[i].x-p[i-1].x)/(p[i].y-p[i-1].y)+p[i-1].x;
//        break;
//    }
//    ch[++g] = p2;
//    for(j = i-1 ; j > k; j--)
//    ch[++g] = p[j];
//
//    return fabs(getarea(g,ch));
//}
point intersect(point p1,point p2,point p3,point p4){
    point p;
    double a1,b1,a2,b2,c1,c2,d;
    a1=p1.y-p2.y; b1=p2.x-p1.x; c1=p1.x*p2.y-p2.x*p1.y;
    a2=p3.y-p4.y; b2=p4.x-p3.x; c2=p3.x*p4.x-p4.x*p3.y;
    d=a1*b2-a2*b1;
    p.x=(-c1*b2+c2*b1)/d;
    p.y=(-a1*c2+a2*c1)/d;
    return p;
}
bool pan(point a,point b,double y){
    return dcmp(a.y-y)*dcmp(b.y-y)<=0;
}
double cal(double y,point P[],int n){

    int i,j,k;
   int tot=0;
    point a=point(0,y),b=point(1,y);
    for(i=1;i<n;i++){
        if(pan(P[i],P[i+1],y)){
            ch[tot++]=intersect(P[i],P[i+1],a,b);
            break;
        }
    }
    for(j=i+1;j<n;j++){
        ch[tot++]=P[j];
        if(pan(P[j],P[j+1],y)){
            ch[tot++]=intersect(P[j],P[j+1],a,b);
            break;
        }
    }
    double area=getarea(tot,ch);
    return area;
}
int main()
{
    int t,i,a,n,m;
    cin>>t;
    while(t--)
    {
        scanf("%d",&a);
        scanf("%d",&n);
        minz = INF;
        for(i = 1; i <= n ;i++)
        {
            scanf("%lf%lf",&p[i].x,&p[i].y);
            minz = min(minz,p[i].y);
        }
        scanf("%d",&m);
        for(i = 1; i <= m ;i++)
        {
            scanf("%lf%lf",&q[i].x,&q[i].y);
            minz = min(minz,q[i].y);
        }
        double maxz = min(min(p[1].y,p[n].y),min(q[1].y,q[m].y));
        double lef = minz,rig = maxz,mid;
        while(fabs(rig-lef)>eps)
        {
            mid = (rig+lef)/2.0;
            double s1 = cal(mid,p,n),s2 = cal(mid,q,m);
            if(dcmp(s1+s2-a)>0)
            rig = mid;
            else lef = mid;
        }
        printf("%.3f
",lef);
    }
    return 0;
}