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#include <iostream>
#include <string>
#include <vector>
#include <list>
#include <algorithm>
#include <iterator>
#include <sstream>
#include <assert.h>
using namespace std;
template<class Container, class Iterator>
size_t position(Container&& c, Iterator pos){
return size_t(distance(begin(c), pos));
}
template<class Container, class Iterator, class Iterator2>
string sposition(Container&& c, const pair<Iterator, Iterator2>& pos){
ostringstream r;
r << "(" << position(c, pos.first) << ", " << position(c, pos.second) << ")";
return r.str();
}
template<class Container, class Value>
pair<typename remove_reference<Container>::type::iterator, typename remove_reference<Container>::type::iterator>
binary_search(Container&& source, const Value& item){
assert(is_sorted(begin(source), end(source)));
const auto empty = make_pair(source.end(), source.end());
auto l = begin(source), r=end(source), m=l;
while(true){
if(l==r)
return empty;
const auto lr = distance(l,r);
m = next(l, lr/2);
if(*m<item)
l = m;
if(*m>item)
r = m;
if(*m==item)
break;
if(l!=r && next(l)==r)
return empty;
}
cout<<"part1"<<endl;
auto l1=l, r1=m, l2=m, r2=r;
while(true){
const auto lr1 = distance(l1, r1);
m = next(l1, lr1/2);
if(*m<item)
l1 = m;
if(*m>=item)
r1 = m;
if(l1==r1 || (*l1<item && *r1>=item))
break;
}
cout<<"part2"<<endl;
while(true){
const auto lr2 = distance(l2, r2);
m = next(l2, lr2/2);
if(*m<=item)
l2 = m;
if(*m>item)
r2 = m;
if(l2==r2 || (*l2>=item && (r==r2 || *r2>item)))
break;
}
cout<<"part3"<<endl;
return {r1, next(l2)};
}
int main(){
vector<int> s{5,7,7,7,9,19,23};
list<int> s2(s.begin()+1, s.end());
cout<<sposition(s, binary_search(s, 7))<<endl;
cout<<sposition(s2, binary_search(s2, 7))<<endl;
cout<<sposition(s, binary_search(s, 9))<<endl;
cout<<sposition(s, binary_search(s, 5))<<endl;
cout<<sposition(s, binary_search(s, 23))<<endl;
cout<<sposition(s, binary_search(s, 0))<<endl;
vector<int> e;
cout<<sposition(e, binary_search(e, 0))<<endl;
cout<<sposition(s, binary_search(s, 25))<<endl;
cout<<sposition(s, binary_search(s, 10))<<endl;
return 0;
}
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