【leetcode 952. 按公因数计算最大组件大小】【欧拉筛+并查集】

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

class Solution {
    List<Integer> list = new ArrayList<>();
    int primeNum = 0;
    int[] fa;
    int[] rank;
    int[] map ;

    public static void main(String[] args) {
        Solution solution = new Solution();
        int cnt = solution.largestComponentSize(new int[]{
                12377,95569,53366,10979,43909,40213,22501,359,96269,82847,85829,81154,43423,2801,97049,30053,72049,84779,17659,34033,49663,10159,61283,91771,22153,93991,8779,10357,89213,2791,55465,21061,9017,44777,77876,67343,64661,28631,20107,23557,10201,86737,4534,31481,83761,8977,59743,3659,4479,42577,2011,94063,59233,69777,31957,4909,82633,70709,72977,52973,74216,93109,37328,5591,77323,91857,36259,42743,76739,94697,88339,14801,39982,59473,26153,75689,55201,12293,14669,94819,36545,33403,16183,809,12451,20602,52354,54476,51421,53267,25589,45869,13829,90821,37547,52951,80943,33329,48989,11483,21548,75323,32987,51503,16987,89911,54589,74821,25763,34283,23977,46589,87023,36979,40057,43159,12763,29339,41521,85823,57029,69259,18119,27947,97561,54669,63377,69739,72367,27793,57373,79757,30187,83,83089,47527,69899,43786,26951,84278,36721,58207,81773,60283,79641,29483,87797,76313,30236,54359,16007,99371,44501,42649,14673,95789,31907,66049,93745,93985,4591,12813,5813,89767,41045,3607
        });
        System.out.println(cnt);
    }

    public int largestComponentSize(int[] nums) {
        pre();
        int cnt1 = 0;
        for (int num : nums) {
            int tmp = num;
            if( num == 1){
                cnt1=1;
                continue;
            }
            List<Integer> primes = new ArrayList<>();
            for (int i = 0; i < primeNum && list.get(i) <= tmp && map[tmp] == -1; i++) {
                int p = list.get(i);
                boolean find = false;
                while (tmp % p == 0) {
                    tmp = tmp / p;
                    find = true;
                }
                if (find) {
                    primes.add(i);
                }
            }
            int set0 = map[tmp]>-1?map[tmp]:primes.get(0);
            rank[find(set0)]++;
            for (int j = 0; j < primes.size(); j++) {
                int set = primes.get(j);
                merge(set0, set);
            }

        }
        int max = 0;
        for (int i = 0; i < list.size(); i++) {
            int p = find(i);
            if (rank[p] > max) {
                max = rank[p];
            }
        }
        return Math.max(max,1);
    }

    public void merge(int set0, int set1) {
        int p1 = find(set0);
        int p2 = find(set1);

        if (p1 == p2) {
            return;
        }

        if (rank[p1] > rank[p2]) {
            fa[p2] = p1;
            rank[p1] += rank[p2];
        } else {
            fa[p1] = p2;
            rank[p2] += rank[p1];
        }

    }

    public int find(int set0) {
        int tmp = set0;
        while (fa[tmp] != tmp) {
            tmp = fa[tmp];
        }
        int root = tmp;
        while(fa[set0] != set0){
            int p = fa[set0];
            fa[set0] = root;
            set0 = p;
        }
        return root;
    }

    public void pre() {
        primeNum = 0;
        Arrays.fill(isprime,true);
        for (int i = 2; i <= 100000; i++) {
            if (isprime[i]) {
                primeNum++;
                list.add(i);
            }
            for(int j=i;j<=1_000_00;j+=i){
                isprime[j] = false;
            }
            isprime[i] = true;
        }
        //        System.out.println(primeNum);
        fa = new int[primeNum];
        rank = new int[primeNum];
        for (int i = 0; i < primeNum; i++) {
            fa[i] = i;
            rank[i] = 0;
        }
        map = new int[100001];
        Arrays.fill(map,-1);
        for(int i = 0;i<list.size();i++){
            map[list.get(i)] = i;
        }

    }

    boolean[] isprime = new boolean[100001];
}