Leetcode题解 169. Majority Element

原创于 2016-04-15 20:24:06 发布 · 319 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#leetcode

Leetcode题解专栏收录该内容

80 篇文章

订阅专栏

本文介绍了一种使用HashMap来解决数组中多数元素查找问题的方法。通过遍历数组并利用HashMap记录每个元素出现的次数，最终找到出现次数超过数组长度一半的元素。

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.

You may assume that the array is non-empty and the majority element always exist in the array.

用hashmap即可搞定。

public static int majorityElement(int[] nums) {
        int count;
        int len = nums.length / 2;
        HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
        for (int i = 0; i < nums.length; i++) {
            if (map.get(nums[i]) != null) {
                count = map.get(nums[i]);
                count++;
                map.put(nums[i], count);
            } else {
                map.put(nums[i], 1);
            }
        }
        Iterator it = map.keySet().iterator();
        while (it.hasNext()) {
            int key = (int) it.next();
            if (map.get(key) > len) {
                return key;
            }
        }
        return -1;
    }