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_0217_ContainsDuplicate.java
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_0217_ContainsDuplicate.java
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package com.diguage.algorithm.leetcode;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Objects;
import java.util.Set;
/**
* = 217. Contains Duplicate
*
* https://leetcode.com/problems/contains-duplicate/[Contains Duplicate - LeetCode]
*
* 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:
* [source]
* ----
* Input: [1,2,3,1]
* Output: true
* ----
*
* .Example 2:
* [source]
* ----
* Input: [1,2,3,4]
* Output: false
* ----
*
* .Example 3:
* [source]
* ----
* Input: [1,1,1,3,3,4,3,2,4,2]
* Output: true
* ----
*
* @author D瓜哥, https://www.diguage.com/
* @since 2020-01-05 20:01
*/
public class _0217_ContainsDuplicate {
/**
* Runtime: 9 ms, faster than 58.06% of Java online submissions for Contains Duplicate.
*
* Memory Usage: 44.4 MB, less than 57.76% of Java online submissions for Contains Duplicate.
*/
public boolean containsDuplicate(int[] nums) {
if (Objects.isNull(nums) || nums.length < 2) {
return false;
}
Set<Integer> numSet = new HashSet<>();
for (int num : nums) {
if (numSet.contains(num)) {
return true;
} else {
numSet.add(num);
}
}
return false;
}
/**
* Runtime: 5 ms, faster than 96.50% of Java online submissions for Contains Duplicate.
*
* Memory Usage: 42.1 MB, less than 98.28% of Java online submissions for Contains Duplicate.
*/
public boolean containsDuplicateSort(int[] nums) {
if (Objects.isNull(nums) || nums.length < 2) {
return false;
}
Arrays.sort(nums);
for (int i = 0; i < nums.length - 1; i++) {
if (nums[i] == nums[i + 1]) {
return true;
}
}
return false;
}
public static void main(String[] args) {
_0217_ContainsDuplicate solution = new _0217_ContainsDuplicate();
int[] n1 = {1, 2, 3, 1};
boolean r1 = solution.containsDuplicate(n1);
System.out.println(r1);
}
}