3

This is the function for computing maximum sum of a subarray 

int Solution::maxSubArray(const vector<int> &A) { vector<int>::iterator i; int max_so_far = *A.begin(); int current_max = *A.begin(); for(i = A.begin(); i != A.end(); ++i) { current_max = max(*i,*i+current_max); max_so_far = max(max_so_far,current_max) } return max_so_far;

}

This is the error , I'm getting this for C++11 and not in previous versions. Help me solve this

solution.cpp: In member function 'int Solution::maxSubArray(const std::vector<int>&)': solution.cpp:9:8: error: no match for 'operator=' (operand types are 'std::vector<int>::iterator {aka __gnu_cxx::__normal_iterator<int*, std::vector<int> >}' and 'std::vector<int>::const_iterator {aka __gnu_cxx::__normal_iterator<const int*, std::vector<int> >}') for(i = A.begin(); i != A.end(); ++i) ^ solution.cpp:9:8: note: candidates are: In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0, from /usr/include/c++/4.8/bits/char_traits.h:39, from /usr/include/c++/4.8/ios:40, from /usr/include/c++/4.8/ostream:38, from /usr/include/c++/4.8/iostream:39, from solution.h:7, from solution.cpp:-3: /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note: __gnu_cxx::__normal_iterator<int*, std::vector<int> >& __gnu_cxx::__normal_iterator<int*, std::vector<int> >::operator=(const __gnu_cxx::__normal_iterator<int*, std::vector<int> >&) class __normal_iterator ^ /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note: no known conversion for argument 1 from 'std::vector<int>::const_iterator {aka __gnu_cxx::__normal_iterator<const int*, std::vector<int> >}' to 'const __gnu_cxx::__normal_iterator<int*, std::vector<int> >&' /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note: __gnu_cxx::__normal_iterator<int*, std::vector<int> >& __gnu_cxx::__normal_iterator<int*, std::vector<int> >::operator= (__gnu_cxx::__normal_iterator<int*, std::vector<int> >&&) /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note: no known conversion for argument 1 f
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  • Aside: current_max = max(*i,*i+current_max); is incredibly suspicious, don't you mean current_sum? You are summing A, and max_so_far will only be different if some of the values are negative Commented Oct 20, 2017 at 10:57

4 Answers 4

Reset to default
11

You need to use vector<int>::const_iterator instead of vector<int>::iterator.

If you are working with a compiler that supports C++11 or later version, you can use auto type.

auto i = A.begin();
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3

You can't use a regular iterator to go through const vector.

vector<int>::iterator i must be ::const_iterator i.

See this question What is the difference between const_iterator and non-const iterator in the C++ STL?

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1

Since you are passing the vector as a const, a normal iterator won't do the job. Instead you need a const_iterator for a const vector. 

int Solution::maxSubArray(const vector<int> &A) { vector<int>::const_iterator i; for(i = A.begin(); i != A.end(); ++i) { .... }

That should fix it for you!

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0

The iterator needs to be a const_iterator as the parameter is const vector<int>

Change the line

vector<int>::iterator i;

to

vector<int>::const_iterator i;

Or use auto to get the type

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