Flip

• Time : $O(n)$
• Space : $O(1)$

vector<int> Solution::flip(string A) {
    if(count(begin(A), end(A), '1') == A.size()) return {};
    int now = 0, ma = 0, map = 0, pick = 0, n = A.size();
    vector<int> res;
    for(int i = 0; i < n; i++) {
        if(A[i] == '1') now += 1;
        else now -= 1;
        if(now > ma) {
            ma = now;
            map = i + 1;
        }
        if(ma - now > pick) {
            pick = ma - now;
            res = {map + 1, i + 1};
        }
    }
    return res;
}