51 lines
999 B
C++
51 lines
999 B
C++
#include"stdio.h"
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#include"string.h"
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#include"stdlib.h"
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#include"math.h"
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#define e 1e-9
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int n;
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int a[10011],b[10011],c[10011];
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double MAX(double q,double p)
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{
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return q>p?q:p;
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}
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double cal(double x)
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{
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int i;
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double max=-111111111;
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for(i=0;i<n;i++) max=MAX(max,a[i]*x*x+b[i]*x+c[i]);
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return max;
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}
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double solve()
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{
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double left,right,mid,midmid;
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double mid_cal,midmid_cal;
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left=0;
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right=1000;
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while(right-left>e)
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{
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mid=(left+right)/2;
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midmid=(mid+right)/2;
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mid_cal=cal(mid);
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midmid_cal=cal(midmid);
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if(mid_cal>midmid_cal) left=mid;
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else right=midmid;
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}
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return cal(right);
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}
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int main()
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{
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int T;
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int i;
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double ans;
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scanf("%d",&T);
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while(T--)
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{
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scanf("%d",&n);
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for(i=0;i<n;i++) scanf("%d%d%d",&a[i],&b[i],&c[i]);
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ans=solve();
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printf("%.4lf\n",ans);
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}
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return 0;
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}
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