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219. 存在重复元素 II

English Version

题目描述

给定一个整数数组和一个整数 k，判断数组中是否存在两个不同的索引 i 和 j，使得 nums [i] = nums [j]，并且 i 和 j 的差的 绝对值 至多为 k。

 

示例 1:

输入: nums = [1,2,3,1], k = 3
输出: true

示例 2:

输入: nums = [1,0,1,1], k = 1
输出: true

示例 3:

输入: nums = [1,2,3,1,2,3], k = 2
输出: false

解法

Python3

class Solution:
    def containsNearbyDuplicate(self, nums: List[int], k: int) -> bool:
        helper = {}
        for i, v in enumerate(nums):
            if v in helper and i - helper[v] <= k:
                return True
            helper[v] = i
        return False

Java

class Solution {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        Map<Integer, Integer> helper = new HashMap<>();
        for (int i = 0, n = nums.length; i < n; ++i) {
            if (helper.containsKey(nums[i])) {
                int j = helper.get(nums[i]);
                if (i - j <= k) {
                    return true;
                }
            }
            helper.put(nums[i], i);
        }
        return false;
    }
}

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