[leetcode 217] Contains Duplicate

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

 

난이도 쉬움

여러가지 방법이 있다.

 

1. 소팅 사용

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        
        int n = nums.size();
        sort(nums.begin(), nums.end());
        
        for(int i=0; i<n-1; i++){
            if(nums[i] == nums[i+1]){

                return true;
            }
        }
        return false;
    }
};

 

2. set 사용

set이 많이 느리넴..

class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
      
        set<int> s;
        for(int i=0; i<nums.size(); i++){
            if(s.find(nums[i]) != s.end())
                return true;
            s.insert(nums[i]);
        }
        
        return false;
    }
};