Apartments

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main() {
    int n, m, k;
    cin >> n >> m >> k;

    vector<int> applicants(n);
    vector<int> apartments(m);

    // Reading applicants' desired sizes
    for (int i = 0; i < n; ++i) {
        cin >> applicants[i];
    }

    // Reading apartments' sizes
    for (int i = 0; i < m; ++i) {
        cin >> apartments[i];
    }

    // Sorting both lists
    sort(applicants.begin(), applicants.end());
    sort(apartments.begin(), apartments.end());

    int i = 0, j = 0;  // Pointers for applicants and apartments
    int matches = 0;

    // Two-pointer technique to match applicants to apartments
    while (i < n && j < m) {
        if (apartments[j] < applicants[i] - k) {
            // Apartment too small for this applicant
            ++j;
        } else if (apartments[j] > applicants[i] + k) {
            // Apartment too large for this applicant
            ++i;
        } else {
            // Suitable apartment found
            ++matches;
            ++i;
            ++j;
        }
    }

    // Output the number of matched applicants
    cout << matches << endl;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED