mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
99 lines
2.3 KiB
C++
99 lines
2.3 KiB
C++
#include<stdio.h>
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#include<math.h>
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#include<string.h>
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#include<stdlib.h>
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#include <algorithm>
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using namespace std;
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const double eps = 1e-8;
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const double pi = acos(-1.0);
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int n;
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struct point {
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double x, y;
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point operator - (const point& t) const {
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point tmp;
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tmp.x = x - t.x;
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tmp.y = y - t.y;
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return tmp;
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}
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point operator + (const point& t) const {
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point tmp;
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tmp.x = x + t.x;
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tmp.y = y + t.y;
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return tmp;
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}
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bool operator == (const point& t) const {
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return fabs(x-t.x) < eps && fabs(y-t.y) < eps;
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}
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}p[220];
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bool cmpxy(point a,point b)
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{
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if(a.y!=b.y) return a.y<b.y;
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return a.x<b.x;
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}
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double xmult(point p1,point p2,point p0){
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return (p1.x-p0.x)*(p2.y-p0.y)-(p2.x-p0.x)*(p1.y-p0.y);
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}
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inline double cross(point a, point b, point c) {
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return (b.x-a.x)*(c.y-a.y) - (c.x-a.x)*(b.y-a.y);
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}
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inline double dis(point a, point b) {
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return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
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}
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void Grahamxy(point *p, int &n) {
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if ( n < 3 )
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return;
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int i, m=0, top=1;
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sort(p, p+n, cmpxy);
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for (i=n; i < 2*n-1; i++)
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p[i] = p[2*n-2-i];
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for (i=2; i < 2*n-1; i++) {
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while ( top > m && cross(p[top], p[i], p[top-1]) < eps )
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top--;
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p[++top] = p[i];
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if ( i == n-1 ) m = top;
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}
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n = top;
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}
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inline double PLdis(point p,point l1,point l2){
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return fabs(cross(p,l1,l2))/dis(l1,l2);
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}
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void judge(point a,point b,double &len)
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{
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double max=0;
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for(int i=0;i<n;i++)
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{
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double tmp=PLdis(p[i],a,b);
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if(tmp>max)
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max=tmp;
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}
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len=max;
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}
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double solve()
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{
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int i,j;
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double tmp;
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double ans=((__int64)1<<62);
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for(i=0;i<n;i++)
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{
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judge(p[i],p[i+1],tmp);
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if(tmp<ans)
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ans=tmp;
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}
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return ans;
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}
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int main()
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{
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int i,j;
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int cases=1;
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while(scanf("%d",&n),n)
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{
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for(i=0;i<n;i++)
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scanf("%lf%lf",&p[i].x,&p[i].y);
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Grahamxy(p,n);
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p[n]=p[0];
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double ans=solve();
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printf("Case %d: %.2lf\n",cases++,ans+0.005);
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}
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return 0;
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}
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