#Leetcode# 219. Contains Duplicate II
https://leetcode.com/problems/contains-duplicate-ii/
Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.
Example 1:
Input: nums = [1,2,3,1], k = 3
Output: true
Example 2:
Input: nums = [1,0,1,1], k = 1
Output: true
Example 3:
Input: nums = [1,2,3,1,2,3], k = 2
Output: false
代码:
class Solution { public: bool containsNearbyDuplicate(vector<int>& nums, int k) { unordered_map<int, int> m; for (int i = 0; i < nums.size(); ++i) { if (m.find(nums[i]) != m.end() && i - m[nums[i]] <= k) return true; else m[nums[i]] = i; } return false; } };
unordered_map<int, int> mp 查找 值 x 存在:① mp.find(x) != mp.end(); ② mp.count(x) != 0;
自己写了一个 $O(n^2)$ 的代码 不出所料的挂掉了 然后查了一下 unordered_map 的用法 $O(logn)$ 的时间还是很快的 比我写的那个不知道快到哪里去了 但是一个 Easy 题被我搞成这样也太凉了吧