whats wrong in this code?
Money change(stl)
@tishya_goyal, your logic is not correct ,as the lower_bound() method in C++ is used to return an iterator pointing to the first element in the range [first, last) which has a value not less than val.
so if you pass 168 in your lower bound function then it will return iterator to 200 , since 200 is the first value not less than 168 , and since you subtract 1 from the index you will get a[res] as 100,
but if you have 200 , then you will get iterator for 200 and when you subtract 1 from the index you will get index for 100 which should not be the case as 200 can be exchanged for 1 note of 200
so what you can do is pass comparator function to your lower bound function , so what happens with comparator function is the function will return the index for first element which comparator function returns false.
So, the comparator used here is :-
bool comparator(int a,int b){
return a<=b;
}
b will be the key and a will be the elements of the array
you can refer to this discussion for some more info on comparator function :-
I have corrected your code here :-
In case of any doubt feel free to ask 
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