題目描述
難度級別:簡單
Given an array of integers, find if the array contains any duplicates.
Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.
Example 1:
Input: [1,2,3,1]
Output: true
Example 2:
Input: [1,2,3,4]
Output: false
Example 3:
Input: [1,1,1,3,3,4,3,2,4,2]
Output: true
解題思路
哈希表
遍歷數組元素,將數組元素存入哈希表中,若元素已在哈希表中輸出true。
const containsDuplicate = function(nums) {
const hashMap = new Map()
for (let i = 0; i < nums.length; i++) {
if (!hashMap.has(nums[i]))
hashMap.set(nums[i], i)
else
return true
}
return false
};
排序
將數組排序後,若存在相同值則必然是連着的。
const containsDuplicate = function(nums) {
nums.sort()
for (let i = 0; i < nums.length; i++)
if (nums[i] === nums[i+1]) return true
return false
};
集合Set
通過集合去重數組,比較2者元素的數量。
const containsDuplicate = nums =>
new Set(nums).size !== nums.length
題目來源:力扣(LeetCode)
鏈接:https://leetcode-cn.com/problems/contains-duplicate