2899. Last Visited Integers

Given a 0-indexed array of strings words where words[i] is either a positive integer represented as a string or the string "prev".

Start iterating from the beginning of the array; for every "prev" string seen in words, find the last visited integer in words which is defined as follows:

• Let k be the number of consecutive "prev" strings seen so far (containing the current string). Let nums be the 0-indexed array of integers seen so far and nums_reverse be the reverse of nums, then the integer at (k - 1)th index of nums_reverse will be the last visited integer for this "prev".
• If k is greater than the total visited integers, then the last visited integer will be -1.

Return an integer array containing the last visited integers.

class Solution {
public:
    vector<int> lastVisitedIntegers(vector<string>& words) {
        vector<int> res;
        vector<int> st;
        int cons = 0;
        for(auto w : words) {
            if(w == "prev") {
                cons += 1;
                if(st.size() < cons) {
                    res.push_back(-1);
                } else res.push_back(st[st.size() - cons]);
            } else {
                cons = 0;
                st.push_back(stoi(w));
            }
        }
        return res;
    }
};