C++ to Java Conversion: Efficiently Finding Gaps in 2D Grids

import java.util.*;

public class GridGaps {

    static final int N = 60009;
    static final int INF = 0x3f3f3f3f;
    static final double EPS = 1e-8;

    static ArrayList<Integer> Lx[] = new ArrayList[N];
    static ArrayList<Integer> Ly[] = new ArrayList[N];
    static int n, m, k;

    static int fin(int x, int y) {
        int l = 0, r = Lx[x].size() - 1, mid, ans = 0;
        while (l <= r) {
            mid = (l + r) >> 1;
            if (Lx[x].get(mid) <= y) {
                ans = mid;
                l = mid + 1;
            } else {
                r = mid - 1;
            }
        }
        if (Lx[x].get(ans) == y && Lx[x].get(ans + 1) == y + 2) return 1;
        return 0;
    }

    static int solve() {
        int ret = 0;
        for (int i = 1; i < n; i++) {
            for (int j = 1; j < Lx[i].size(); j++) {
                if (Lx[i].get(j) - Lx[i].get(j - 1) > 2) {
                    ret++;
                }
            }
        }
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < Ly[i].size(); j++) {
                if (Ly[i].get(j) - Ly[i].get(j - 1) > 2) {
                    ret++;
                }
                if (Ly[i].get(j) - Ly[i].get(j - 1) == 2) {
                    if (fin(Ly[i].get(j) - 1, i - 1)) {
                        ret++;
                    }
                }
            }
        }
        return ret;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();
        k = sc.nextInt();
        int a, b;
        Lx = new ArrayList[n + 1];
        Ly = new ArrayList[m + 1];
        for (int i = 0; i <= n; i++) {
            Lx[i] = new ArrayList<>();
        }
        for (int i = 0; i <= m; i++) {
            Ly[i] = new ArrayList<>();
        }
        for (int i = 0; i < k; i++) {
            a = sc.nextInt();
            b = sc.nextInt();
            Lx[a].add(b);
            Ly[b].add(a);
        }
        n++;
        m++;
        for (int i = 1; i <= n; i++) {
            Lx[i].add(0);
            Lx[i].add(m);
        }
        for (int i = 1; i <= m; i++) {
            Ly[i].add(0);
            Ly[i].add(n);
        }
        for (int i = 1; i <= n; i++) {
            Collections.sort(Lx[i]);
        }
        for (int i = 1; i <= m; i++) {
            Collections.sort(Ly[i]);
        }
        System.out.println(solve());
    }
}