56 lines
1.3 KiB
JavaScript
56 lines
1.3 KiB
JavaScript
/*
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* @lc app=leetcode id=217 lang=javascript
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*
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* [217] Contains Duplicate
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*
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* https://leetcode.com/problems/contains-duplicate/description/
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*
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* algorithms
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* Easy (50.92%)
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* Total Accepted: 324K
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* Total Submissions: 628.5K
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* Testcase Example: '[1,2,3,1]'
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*
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* Given an array of integers, find if the array contains any duplicates.
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*
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* Your function should return true if any value appears at least twice in the
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* array, and it should return false if every element is distinct.
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*
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* Example 1:
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*
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*
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* Input: [1,2,3,1]
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* Output: true
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*
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* Example 2:
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*
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*
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* Input: [1,2,3,4]
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* Output: false
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*
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* Example 3:
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*
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*
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* Input: [1,1,1,3,3,4,3,2,4,2]
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* Output: true
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*
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*/
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/**
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* @param {number[]} nums
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* @return {boolean}
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*/
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var containsDuplicate = function(nums) {
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// 1. 暴力两层循环两两比较， 时间复杂度O(n^2) 空间复杂度O(1)
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// 2. 先排序，之后比较前后元素是否一致即可，一层循环即可，如果排序使用的比较排序的话时间复杂度O(nlogn) 空间复杂度O(1)
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// 3. 用hashmap ，时间复杂度O(n) 空间复杂度O(n)
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const visited = {};
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for(let i = 0; i < nums.length; i++) {
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if (visited[nums[i]]) return true;
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visited[nums[i]] = true;
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}
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return false;
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};
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