codeforces maxsubarray

B.fg.cpp

#include <stdio.h>
#include <iostream>

using namespace std;

int main()
{
    int n, min_i = 0, max_i = 0, tmp_i = 0, max_sum=0, curr_sum=0;
    cin >> n;
    int arr[n];
    int binarr[n];

    for (int i = 0; i < n; ++i)
    {
        cin >> arr[i];

        if (arr[i]==0)
            binarr[i] = 1;
        else
            binarr[i] = -1;
    }

    //get start and end index of change
    for (int i = 0; i < n; ++i)
    {
        curr_sum += binarr[i];
        if (curr_sum < 0) {
            curr_sum = 0;
            tmp_i = i+1;
        }

        if (max_sum < curr_sum) {
            max_sum = curr_sum;
            min_i = tmp_i;
            max_i = i;
        }
    }

    //sum one's
    int sum = 0;
    for (int i = 0; i < n; ++i)
    {
        if (i < min_i || i > max_i){
            if (arr[i])
               sum++;
        }
        else{
            if (!arr[i])
               sum++;
        }

    }

    cout << sum;
    return 0;
}