Java求解众数问题和重数问题的具体代码

众数问题（求一个数组中出现次数最多的数）：

public static int findMode(int[] nums) {
    if (nums == null || nums.length == 0) {
        throw new IllegalArgumentException("Input array is empty");
    }
    Map<Integer, Integer> map = new HashMap<>();
    int maxCount = 0;
    int mode = 0;
    for (int num : nums) {
        int count = map.getOrDefault(num, 0) + 1;
        map.put(num, count);
        if (count > maxCount || (count == maxCount && num < mode)) {
            maxCount = count;
            mode = num;
        }
    }
    return mode;
}

重数问题（求一个数组中所有出现次数等于给定值的数）：

public static List<Integer> findElementsWithGivenCount(int[] nums, int count) {
    if (nums == null || nums.length == 0) {
        throw new IllegalArgumentException("Input array is empty");
    }
    Map<Integer, Integer> map = new HashMap<>();
    for (int num : nums) {
        int c = map.getOrDefault(num, 0) + 1;
        map.put(num, c);
    }
    List<Integer> result = new ArrayList<>();
    for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
        if (entry.getValue() == count) {
            result.add(entry.getKey());
        }
    }
    return result;
}