current position:Home>[leetcode] 38. There are duplicate elements - Java version

[leetcode] 38. There are duplicate elements - Java version

2021-08-26 16:37:32 One coding

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java Set Self weight removal , If the length after weight removal is less than the original length , Then return to true

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Preface

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Question

217. There are duplicate elements

difficulty : Simple

Given an array of integers , Determine whether there are duplicate elements .

If a value exists, it appears at least twice in the array , The function returns true . If every element in the array is different , Then return to false .

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

Solution

hashset

  • utilize hashset The principle of weight removal
  • If you return... When adding an element false, There is

Code

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/** * @author yitiaoIT */
class Solution {
    
    public boolean containsDuplicate(int[] nums) {
    
        Set<Integer> set = new HashSet<Integer>();
        for (int x : nums) {
    
            if (!set.add(x)) {
    
                return true;
            }
        }
        return false;
    }
}

Result

Complexity analysis

  • Time complexity :O(N)

image-20210822222840620

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