Stock buy and sell

The cost of stock on each day is given in an array A[] of size N. Find all the days on which you buy and sell the stock so that in between those days your profit is maximum.

• Time : O(n)
• Space : O(n)

void stockBuySell(int A[], int n) {
    vector<pair<int,int>> st;
    for(int i = 0; i < n - 1; i++) {
        if(A[i] < A[i + 1]) {
            if(st.empty() or st.back().second != i) st.push_back({i, i + 1});
            else st.back().second = i + 1;
        }
    }
    if(st.empty()) cout<<"No Profit";
    
    for(auto& p : st) {
        cout<<"("<<p.first<<' '<<p.second<<") ";
    }
    cout<<endl;
}