2343. Query Kth Smallest Trimmed Number

You are given a 0-indexed array of strings nums, where each string is of equal length and consists of only digits.

You are also given a 0-indexed 2D integer array queries where queries[i] = [ki, trimi]. For each queries[i], you need to:

• Trim each number in nums to its rightmost trimi digits.
• Determine the index of the kith smallest trimmed number in nums. If two trimmed numbers are equal, the number with the lower index is considered to be smaller.
• Reset each number in nums to its original length.

Return an array answer of the same length as queries, where answer[i] is the answer to the ith query.

Note:

• To trim to the rightmost x digits means to keep removing the leftmost digit, until only x digits remain.
• Strings in nums may contain leading zeros.

class Solution {
    int helper(vector<string>& A, int k, int cut) {
        vector<pair<string, int>> B;
        for(int i = 0; i < A.size(); i++) {
            B.push_back({A[i].substr(A[i].length() - cut), i});
        }
        sort(begin(B), end(B));
        return B[k-1].second;
    }
public:
    vector<int> smallestTrimmedNumbers(vector<string>& nums, vector<vector<int>>& queries) {
        vector<int> res;
        for(auto& q : queries) {
            res.push_back(helper(nums, q[0], q[1]));
        }
        return res;
    }
};