Vectors C++ Out Of Range Exception

[SabeelAhmad]

I was working on an assignment where I have to work with vector of strings, However when I run the program it throws and Exception of being out of range when _n = 0. Any help would be appreciated.

  #include<iostream>
#include<climits>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;

int LCP(string a, string b) {
    int x = 0;
    for(int i = 0, j = 0; i < a.length() && j < b.length(); i++, j++) {
        if(a[i] == b[j]) {
            x++;
        }
        else {
            break;
        }
    }
    return x;
}

int main() {
    int n;
    cin >> n;
    vector<string> input;
    for(int i = 0; i < n; i++) {
        string str;
        cin >> str;
        input.push_back(str);
    }
    int q;
    for(int j = 1; j <= q; j++) {
        int r;
        cin >> r;
        string p;
        cin >> p;
        vector<int> commonPrefixLengths;
        for(int i = 0; i < r; i++) {
            int length = LCP(input[i], p);
            commonPrefixLengths.push_back(length);
        }
        int maxLength = INT_MIN;
        for(int i = 0; i < r; i++) {
            if(commonPrefixLengths[i] > maxLength) {
                maxLength = commonPrefixLengths[i];
            }
        }
        vector<string> toBeSorted;
        for(int i = 0; i < n; i++) {
            if(input[i].size() == maxLength) {
                toBeSorted.push_back(input[i]);
            }
        }
        sort(toBeSorted.begin(), toBeSorted.end());
        cout << toBeSorted[0] << endl;
    }
}

[Repeater]

toBeSorted is empty

[SabeelAhmad]

But in the last for loop I'm using the push_back operator to insert elements in to the toBeSorted vector.

[Repeater]

But you're pushing nothing into it.

Check for yourself:

cout << "Size of toBeSorted: " << toBeSorted.size();