package com.ks;
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import org.junit.jupiter.api.Test;
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import java.util.*;
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public class LuckyTest {
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@Test
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public void test() {
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Map<Long, Integer> map = new HashMap<>();
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int total = 0;
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int personCount = 1000000;
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for (int i = 0; i < personCount; i++) {
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map.put(10000L + i, i == 0 ? 0 : (int) (1 + 10 * Math.random()));
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total += map.get(10000L + i);
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}
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Set<Long> sets = choujiang(map, 100);
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int percent = total / personCount;
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int upCount = 0;
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for (Long uid : sets) {
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if (map.get(uid) > percent)
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upCount += 1;
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System.out.println(uid + "-" + map.get(uid) + "是否大于均值：" + (map.get(uid) > percent));
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}
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System.out.println("大于均值数量:" + upCount);
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System.out.println("数量:" + sets.size());
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}
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private Set<Long> choujiang(Map<Long, Integer> map, int number) {
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List<Long> mList = new ArrayList<>();
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for (Iterator<Long> its = map.keySet().iterator(); its.hasNext(); ) {
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Long uid = its.next();
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int c = map.get(uid);
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for (int i = 0; i < c; i++) {
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mList.add(uid);
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}
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}
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Set<Long> luckyUids = new HashSet<>();
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for (int i = 0; i < number; i++) {
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if(mList.size()==0)
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break;
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long startTime = System.currentTimeMillis();
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int p = (int) (mList.size() * Math.random());
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long uid = mList.get(p);
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luckyUids.add(uid);
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//移除列表右面的相同uid
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while (mList.size() > p && mList.get(p) == uid) {
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mList.remove(p);
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}
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//查询相同uid的列表左侧起点
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for (int j = p - 1; j >= 0; j--) {
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if (mList.get(j).longValue() != uid) {
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p = j + 1;
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break;
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} else if (j == 0) {
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p = 0;
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}
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}
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//删除左侧相同uid
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while (mList.size() > p && mList.get(p) == uid) {
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mList.remove(p);
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}
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System.out.println("运行时间：" + (System.currentTimeMillis() - startTime));
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}
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System.out.println(luckyUids);
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return luckyUids;
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}
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}
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