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I have a vector of unordered_map which is sorted based on the comparer function I defined. I would like to use binary search to look for one of the value using the comparer function as well. However, binary search only return bool and I need the index / iterator of the result. What could I do?
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Binary search is a widely used searching algorithm that requires the array to be sorted before search is applied.
1. binary_search: binary_search(start_ptr, end_ptr, num): This function returns true if the element is present in the container, else returns false.
C++ bsearch()The bsearch() function in C++ performs a binary search of an element in an array of elements and returns a pointer to the element if found. The bsearch() function requires all elements less than the element to be searched to the left of it in the array.
A Binary Search is a sorting algorithm, that is used to search an element in a sorted array. A binary search technique works only on a sorted array, so an array must be sorted to apply binary search on the array.
#include <algorithm>
using namespace std;
//!!!!! a must be sorted using cmp. Question indicates that it is.
it = lower_bound(a.begin, a.end(), value, cmp);
//Check that we have actually found the value.
//If the requested value is missing
//then we will have the value before where the requested value
//would be inserted.
if(it == a.end() || !cmp(*it, value))
{
//element not found
}
else
{
//element found
}
#include <algorithm>
using namespace std;
it = lower_bound(a.begin, a.end(), value, cmp);
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