leetcode (Longest Harmonious Subsequence)

Title:Longest Harmonious Subsequence    594

Difficulty:Easy

原题leetcode地址: https://leetcode.com/problems/longest-harmonious-subsequence/

 

1.  采用map

时间复杂度:O(n),两次一层循环,最长遍历数组长度。

空间复杂度:O(n),申请map。

    /**
     * 采用map
     * @param nums
     * @return
     */
    public static int findLHS(int[] nums) {

        int count = 0;
        Map map = new HashMap<>();

        for (int num : nums) {
            map.put(num, map.getOrDefault(num, 0) + 1);
        }

        for (int key : map.keySet()) {
            if (map.containsKey(key + 1)) {
                count = Math.max(count, map.get(key + 1) - map.get(key));
            }
        }

        return count;

    }

 

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