在数组中找到出现次数大于n/k的数

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mb5fed6ec4336ce 2021-10-14 10:25:00

给定一个整型数组arr，再给定一个整数k，打印所有出现次数大于n/k的数，如果没有这样的数,请打印”-1“。

import java.util.*;

public class Main {

private static void reduceOne(Map<Integer, Integer> candidateMap) {
Iterator<Map.Entry<Integer, Integer>> iterator = candidateMap.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry<Integer, Integer> next = iterator.next();
if (next.getValue() == 1) {
iterator.remove();
            } else {
next.setValue(next.getValue() - 1);
            }
        }
    }

private static List<Integer> solve(int[] arr, int k) {
int n = arr.length;

Map<Integer, Integer> candidateMap = new HashMap<>();

for (int num : arr) {
if (candidateMap.containsKey(num)) {
candidateMap.put(num, candidateMap.get(num) + 1);
            } else {
if (candidateMap.size() < k) {
candidateMap.put(num, 1);
                } else {
reduceOne(candidateMap);
                }
            }
        }

List<Integer> ret = new ArrayList<>();
Map<Integer, Integer> countMap = new HashMap<>();

for (int num : arr) {
if (candidateMap.containsKey(num)) {
Integer count = countMap.getOrDefault(num, 0);
if (count == n / k) {
ret.add(num);
                }
countMap.put(num, count + 1);

            }
        }
return ret;
    }

private static void print(List<Integer> ret) {
if (ret.size() == 0) {
System.out.println(-1);
return;
        }

StringBuilder sb = new StringBuilder();
for (int num : ret) {
sb.append(num).append(" ");
        }
System.out.println(sb.toString().trim());
    }

public static void main(String[] args) {
Scanner in = new Scanner(System.in);
while (in.hasNext()) {
int n = in.nextInt();
int k = in.nextInt();
int[] arr = new int[n];
for (int i = 0; i < n; ++i) {
arr[i] = in.nextInt();
            }
List<Integer> ret = solve(arr, k);
print(ret);
        }
    }
}