77 lines
1.5 KiB
C++
77 lines
1.5 KiB
C++
#include<cstdio>
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#include<cstring>
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#include<iostream>
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#include<algorithm>
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#include<cmath>
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#include<vector>
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using namespace std;
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const int maxn=55;
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const int inf=1<<29;
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const double eps=1e-6;
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int n;
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double a[maxn],dp[maxn][2];
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vector<double> set;
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bool check(double val)
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{
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bool last=false;
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for(int i=1;i<n-1;i++)
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{
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if(!last&&a[i]-a[i-1]>=val)
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{
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last=false;
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continue;
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}
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if(last&&fabs(a[i]-a[i-1]-val)<=eps)
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{
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last=false;
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continue;
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}
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if(last&&(a[i]-a[i-1])/2>=val)
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{
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last=false;
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continue;
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}
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if(a[i+1]-a[i]>=val)
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{
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last=true;
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continue;
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}
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return false;
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}
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return true;
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}
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int main()
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{
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int T;
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scanf("%d",&T);
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while(T--)
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{
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memset(dp,0,sizeof(dp));
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scanf("%d",&n);
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for(int i=0;i<n;i++)
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scanf("%lf",&a[i]);
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sort(a,a+n);
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n=unique(a,a+n)-a;
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if(n<=2)
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{
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printf("0.000\n");
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continue;
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}
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for(int i=1;i<n;i++)
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{
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set.push_back(a[i]-a[i-1]);
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set.push_back((a[i]-a[i-1])/2);
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}
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sort(set.begin(),set.end());
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double ans=0;
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for(int i=set.size()-1;i>=0;i--)
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if(check(set[i]))
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{
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ans=set[i];
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break;
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}
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printf("%.3f\n",ans);
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}
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return 0;
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}
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