hdu 1007

hdu 1007

详细解释

#include<bits/stdc++.h>
#define inf  0x7fffffff
#define linf 0x7fffffffffffffff
#define fil(x,y) memset(x,y,sizeof(x))
#define fup(i,x,y) for(int i=(x);i<=(y);i++)
#define fdn(i,x,y) for(int i=(x);i>=(y);i--)
#define sp(x) setprecision(x)
#define sd(n) scanf("%d",&n)
#define sdd(n,m) scanf("%d%d",&n,&m)
#define sddd(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define sld(n) scanf("%lld",&n)
#define sldd(n,m) scanf("%lld%lld",&n,&m)
#define slddd(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define sf(n) scanf("%lf",&n)
#define sff(n,m) scanf("%lf%lf",&n,&m)
#define sfff(n,m,k) scanf("%lf%lf%lf",&n,&m,&k)
#define sc(n) scanf("%s",n)
#define lowbit(x) (x&(-x))
#define pf(x) printf("%d\n",x)
#define pfl(x) printf("%lld\n",x)
#define pff(x) printf("%lf\n",x)
#define debug printf("!!\n");
#define N 1000005
#define M 4000009
#define pi acos(-1)
#define eps 1e-2
//cout.setf(ios::fixed);
//freopen("out.txt","w",stdout);// freopen("in.txt","r",stdin);
using namespace std;
typedef long long  ll;
typedef double db;
using namespace std;
typedef long long ll;
using namespace std;
struct node
{
    double x,y;
    bool operator <(const node &a) const
    {
        if(x==a.x) return y<a.y;
        return x<a.x;
    }
} a[100005];
db dfs(int l,int r,vector<int > &t)
{
    if(r-l<=1)
    {
        if(l==r)
        {
            t.push_back(l);
            return inf;
        }
        t.push_back(l),t.push_back(r);
        return (a[l].x-a[r].x)*(a[l].x-a[r].x)+(a[l].y-a[r].y)*(a[l].y-a[r].y);
    }
    vector<int> tl,tr;
    int mid=(l+r)>>1;
    db minn=min(dfs(l,mid,tl),dfs(mid+1,r,tr));
    int st1,st2;
    st1=st2=0;
    int n=tl.size(),m=tr.size();
    while(st1<n||st2<m)
    {
        if(st2>=m||(st1<n&&a[tl[st1]].y<a[tr[st2]].y)) t.push_back(tl[st1++]);
        else t.push_back(tr[st2++]);
    }
    n=t.size();
    for(int i=0;i<n;i++)
        for(int j=i+1;j<min(n,i+7);j++)
            minn=min(minn,(a[t[i]].x-a[t[j]].x)*(a[t[i]].x-a[t[j]].x)+(a[t[i]].y-a[t[j]].y)*(a[t[i]].y-a[t[j]].y));
    return minn;
}
int main()
{
    int n;
    while(~sd(n) && n)
    {
        for(int i=0; i<n; i++)
            scanf("%lf %lf",&a[i].x,&a[i].y);
        sort(a,a+n);
        vector<int> t;
        printf("%.2f\n",sqrt(dfs(0,n-1,t))/2);
    }
    return 0;
}