27 lines
720 B
C
27 lines
720 B
C
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#ifndef _BISECTION_H
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#define _BISECTION_H
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//general bisection search
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//returns dm-1 on failure, otherwise number between dm and hm
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template<typename INDEX, typename COMPAR, typename SUBJECT>
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INDEX bisection_find(INDEX dm, INDEX hm, const SUBJECT *key, const SUBJECT *base , unsigned int lead_dimension_base, COMPAR (*cmp)(const SUBJECT *, const SUBJECT *))
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{
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if(dm>hm) return(dm-1);
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if(dm==hm) return (*cmp)(base+dm*lead_dimension_base,key)? dm-1 :dm;
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INDEX sm;
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INDEX dm0=dm;
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--dm;
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++hm;
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do
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{
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sm = (dm+hm)/2;
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COMPAR q = (*cmp)(base+sm*lead_dimension_base,key);
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if (!q) return(sm);
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else if (q<0) dm = sm; else hm = sm;
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}
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while (hm > dm+1);
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return(dm0-1);
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}
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#endif
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