CSES Planet Cycles

Problem Info

I used the same solution as USACO guide for the Planet Cyles problem. However, it times out on 1 test case. Can someone please have a look for me and tell me why it is timing out? Is it because I am using Java?

My Work

import java.io.*;
import java.util.*;

class cses {
    static int n;
    static boolean[] used;
    static LinkedList<Integer> cycle = new LinkedList<>();
    static int steps;
    static int[] arr;
    static int[] ans;
    public static void main(String[] args) throws IOException{
        BufferedReader file = new BufferedReader(new InputStreamReader(System.in));
        //BufferedReader file = new BufferedReader(new FileReader("paint.in"));
        StringTokenizer st = new StringTokenizer(file.readLine());
        n = Integer.parseInt(st.nextToken());
        arr = new int[n];
        st = new StringTokenizer(file.readLine());
        for (int i=0; i<n; i++){
            arr[i] = Integer.parseInt(st.nextToken())-1;
        ans = new int[n];
        used = new boolean[n];
        for (int i=0; i<n; i++){
            if (!used[i]){
                steps = 0;
                int decrease = 1;
                int last = cycle.peekLast();
                while (!cycle.isEmpty()){
                    if (cycle.peekFirst().equals(last)){
                        decrease = 0; // no need to decrease
                    int index = cycle.poll();
                    ans[index] = steps;
                    steps -= decrease;
        for (int i : ans){
            System.out.print(i + " ");
    public static void dfs(int curr){
        used[curr] = true;
        int next = arr[curr];
        if (!used[next]){
            steps += ans[next];


The thinking is just trying to find all the cycles, and all elements within the cycle should have the same answer for how many travels before returning to a “used” planet. For a node that connects to a cycle but isn’t in the cycle itself, the answer will be greater than those connected in the cycle. We will process those not in the cycle first and decrease the “steps” variable, and eventually, we will reach nodes that are in the cycle and we don’t need to decrease anymore.

My question

I think the program will only pass through every node once because it will return once it sees a used node. Therefore, I am don’t understanding why it is timing out?

It seems there’s some fields you haven’t filled out. Maybe try doing so?

Thanks for replying, what do you mean by fields?

Nevermind, it seems you filled them out. I’ll take a look at your code.

try doing I/O with kattio

Why is kattio faster?

If the data is particularly long this might help. Also, not all CSES problems are solvable with Java, so if you’re sure the time complexity is right (download the data, run it locally, make sure it only takes a few seconds) then you can probably just skip the problem.