C++博客-huicpc0860-随笔分类-Computational Geometry

hdu 2993 MAX Average Problem

huicpc0860 — Mon, 09 Aug 2010 12:24:00 GMT

#include <stdio.h>
using namespace std;
#define N 100010
#define max(x,y) ((x)>(y)?(x):(y))
typedef long long  LL;
int s[N];
struct point {
    int x, y;
    point(){}
    point(int x,int y):x(x),y(y){}
}p[N];
point operator - (const point &a, const point &b) { return point(a.x-b.x, a.y-b.y); }
LL operator ^ (const point &a, const point &b) { return (LL)a.x*b.y - (LL)a.y*b.x; }
inline int get(){
    int s=0;
    char c;
    while(c=getchar(),c!=' '&&c!='\n')s=s*10+c-'0';
    return s;
}
int main() {
    int n,k;
    s[0]=0;
    while (~scanf("%d ",&n)){
        k=get();n++;
        for(int i=1;i<n;++i){
            s[i]=get();
            s[i]+=s[i-1];
        }
        double ans=0;
        for(int i=k,m=-1,f=0;i<n;++i){
            point now(i-k,s[i-k]);
            while(f<m&&(p[m]-p[m-1]^now-p[m-1])<0)--m;
            p[++m]=now;
            while(f<m&&(LL)(s[i]-p[f].y)*(i-p[f+1].x)<(LL)(s[i]-p[f+1].y)*(i-p[f].x))f++;
            ans=max(ans,double(s[i]-p[f].y)/(i-p[f].x));
        }
        printf("%.2lf\n",ans);
    }
}

huicpc0860 2010-08-09 20:24 发表评论

poj 1133 stars

huicpc0860 — Sun, 01 Aug 2010 12:05:00 GMT

摘要: #include #include #include using namespace std;const double eps=1e-8;int so,mo,br;inline int dcmp(double... 阅读全文

huicpc0860 2010-08-01 20:05 发表评论

poj 1271 Nice Milk

huicpc0860 — Tue, 27 Jul 2010 10:46:00 GMT

#include <stdio.h>
#include <math.h>
#include <algorithm>
using namespace std;
const double eps=1e-8;
double h,ans,cake;
struct point {
    double x,y;
    point (){}
    point (double x,double y):x(x),y(y){}
    void get(){scanf("%lf%lf",&x,&y);}
};
struct poly{
    point p[21];
    int n;
    void get(){for(int i=0;i<n;i++)p[i].get();p[n]=p[0];}
}sg;
int dcmp(double x){
    return (x>eps)-(x<-eps);
}
double cross(point o,point p,point q){
    return (p.x-o.x)*(q.y-o.y)-(p.y-o.y)*(q.x-o.x);
}
point lineinter(point a,point b,point c,point d){
    double u=cross(a,b,c),v=cross(b,a,d);
    return point((c.x*v+d.x*u)/(u+v),(c.y*v+d.y*u)/(u+v));
}
double dis(point a,point b){
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
void push(point a,point b,point &c,point &d){
    double x=a.y-b.y,y=b.x-a.x,t=h/dis(a,b);
    c=point(a.x+x*t,a.y+y*t);
    d=point(b.x+x*t,b.y+y*t);
}
void cut(point a,point b,poly tg,poly &g){
    push(a,b,a,b);
    g.n=0;
    for(int i=0;i<tg.n;i++){
        int u=dcmp(cross(a,b,tg.p[i])),v=dcmp(cross(a,b,tg.p[i+1]));
        if(u>=0)g.p[g.n++]=tg.p[i];
        if(u*v<0) g.p[g.n++]=lineinter(a,b,tg.p[i],tg.p[i+1]);
    }
    g.p[g.n]=g.p[0];
}
double area(poly g){
    double sum=0;
    for(int i=2;i<g.n;i++)
        sum+=cross(g.p[0],g.p[i-1],g.p[i]);
    return 0.5*sum;
}
void dfs(int i,int step,poly g){
    if(step+i<sg.n)dfs(i+1,step,g);
    cut(sg.p[i],sg.p[i+1],g,g);
    if(step==1)ans=max(ans,cake-area(g));
    else dfs(i+1,step-1,g);
}
int main(){
    int k;
    while(scanf("%d%d%lf",&sg.n,&k,&h),sg.n||k||h){
        sg.get();
        cake=area(sg);
        ans=0;
        k=min(k,sg.n);
        if(k&&h)dfs(0,k,sg);
        printf("%.2lf\n",ans);
    }
    return 0;
}

huicpc0860 2010-07-27 18:46 发表评论

poj 3347 Kadj Squares

huicpc0860 — Fri, 23 Jul 2010 10:51:00 GMT

#include <stdio.h>
#include <math.h>
#define max(a,b) (a>b?a:b)
int n;

struct seg {
    double l, r, t;
} a[50];

int main() {
    while (scanf("%d", &n), n) {
        for (int i = 0; i < n; i++) {
            scanf("%lf", &a[i].t);
            a[i].l = 0.0;
            for (int j = 0; j < i; j++)
                a[i].l = max(a[i].l, a[j].r - fabs(a[i].t - a[j].t) / 2);
            a[i].r = a[i].l + a[i].t;
        }
        for (int i = 1; i < n; i++)
            for (int j = 0; j < i; j++)
                if (a[i].l < a[i].r) {
                    if (a[i].t > a[j].t && a[i].l < a[j].r)
                        a[j].r = a[i].l;
                    else if (a[i].t < a[j].t && a[j].r > a[i].l)
                        a[i].l = a[j].r;
                }
        for (int i = 0; i < n; i++)
            if (a[i].l < a[i].r)printf("%d ", i + 1);
        puts("");
    }
}

huicpc0860 2010-07-23 18:51 发表评论

hdu 3437 Garden

huicpc0860 — Wed, 14 Jul 2010 13:39:00 GMT

摘要: #include #include #include #define zero(x) if(dcmp(x)==0)x=0#define cross(p0,p1,p2) ((p1.x-p0.x)*(p2.y-p0.y)-(p1.y-p0.y... 阅读全文

huicpc0860 2010-07-14 21:39 发表评论

poj 1228 Grandpa's Estate

huicpc0860 — Sat, 15 May 2010 13:07:00 GMT

#include <stdio.h>
#include <algorithm>
using namespace std;

struct point {
    int x, y;
};

bool cmp(point p1, point p2) {
    return p1.y < p2.y || p1.y == p2.y && p1.x < p2.x;
}

int cross(point p0, point p1, point p2) {
    return (p1.x - p0.x)*(p2.y - p0.y)-(p1.y - p0.y)*(p2.x - p0.x);
}

void tubao(point *p, int n, point *ch, int &m) {
    int i, k;
    sort(p, p + n, cmp);
    for (m = i = 0; i < n; i++) {
        while (m > 1 && cross(ch[m - 2], ch[m - 1], p[i]) < 0)m--;
        ch[m++] = p[i];
    }
    if (n = m)return;
    k = m;
    for (i = n - 2; i >= 0; i--) {
        while (m > k && cross(ch[m - 2], ch[m - 1], p[i]) < 0)m--;
        ch[m++] = p[i];
    }
    if (n > 1)m--;
}

bool judge(point *p, int n) {
    if (n < 6)return 0;
    for (int i = 2; i < n; i++)
        if (cross(p[0], p[1], p[i]) != 0)return 1;
    return 0;
}

int main() {
    point p[1010], ch[1010];
    int t, n;
    scanf("%d", &t);
    while (t--) {
        scanf("%d", &n);
        for (int i = 0; i < n; i++)
            scanf("%d%d", &p[i].x, &p[i].y);
        bool flag = judge(p, n);
        if (flag) {
            tubao(p, n, ch, n);
            ch[n] = ch[0];
            point a, b;
            for (int i = 1; flag && i < n;) {
                a = ch[i - 1], b = ch[i++];
                flag = 0;
                while (i <= n && cross(a, b, ch[i]) == 0) {
                    flag = 1;
                    i++;
                }
            }
        }
        puts(flag ? "YES" : "NO");
    }
    return 0;
}