Binary Search in C++ Standard Template Library (STL)
Binary search is a widely used searching algorithm that requires the array to be sorted before search is applied. The main idea behind this algorithm is to keep dividing the array in half (divide and conquer) until the element is found, or all the elements are exhausted.
It works by comparing the middle item of the array with our target, if it matches, it returns true otherwise if the middle term is greater than the target, the search is performed in the left sub-array.
If the middle term is less than the target, the search is performed in the right sub-array.
The prototype for binary search is :
binary_search(startaddress, endaddress, valuetofind) Parameters : startaddress: the address of the first element of the array. endaddress: the address of the next contiguous location of the last element of the array. valuetofind: the target value which we have to search for. Returns : true if an element equal to valuetofind is found, else false.
The array is : 1,5,8,9,6,7,3,4,2,0, Let's say we want to search for 2 in the array So, we first sort the array The array after sorting is : 0,1,2,3,4,5,6,7,8,9, Now, we do the binary search Element found in the array Now, say we want to search for 10 Element not found in the array
Time Complexity: sort – O(nlogn), binary_search – O(logn)
Auxiliary Space: O(1)
Related Article: std::bsearch in C++
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