Leetcode
2020.04.16 13:56

# 287. Find the Duplicate Number

조회 수 211 추천 수 0 댓글 0
?

#### 단축키

Prev이전 문서

Next다음 문서

크게 작게 위로 아래로 댓글로 가기 인쇄
?

#### 단축키

Prev이전 문서

Next다음 문서

크게 작게 위로 아래로 댓글로 가기 인쇄

Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one.

Example 1:

```Input: `[1,3,4,2,2]`
Output: 2
```

Example 2:

```Input: [3,1,3,4,2]
Output: 3```

Note:

1. You must not modify the array (assume the array is read only).
2. You must use only constant, O(1) extra space.
3. Your runtime complexity should be less than O(n2).
4. There is only one duplicate number in the array, but it could be repeated more than once.

```class Solution {
public int findDuplicate(int[] nums) {
HashMap<Integer, Integer> hmap = new HashMap<>();

for(int num : nums){
hmap.put(num, hmap.getOrDefault(num,0)+1);
}

for(Map.Entry<Integer, Integer> item : hmap.entrySet()){
if(item.getValue() > 1){
return item.getKey();
}
}

return -1;
}
}```

```class Solution {
public int findDuplicate(int[] nums) {
Set<Integer> set = new HashSet<>();

for(int num : nums){
if(set.contains(num)){
return num;
}
}

return -1;
}
}```

```class Solution {
public int findDuplicate(int[] nums) {
Arrays.sort(nums);

for(int i=1; i<nums.length; i++){
if(nums[i] == nums[i-1]){
return nums[i];
}
}

return -1;
}
}```

?

 제목+내용제목내용댓글이름닉네임아이디태그
List of Articles
번호 분류 제목 글쓴이 날짜 조회 수
» Leetcode 287. Find the Duplicate Number 2020.04.16 211
16 Leetcode 253. Meeting Rooms II 2020.04.15 211
15 Leetcode 731. My Calendar II 2020.04.15 194
14 Leetcode 729. My Calendar I 2020.04.15 187
13 Leetcode 692. Top K Frequent Words 2020.04.15 195
12 Leetcode 973. K Closest Points to Origin 2020.04.15 210
11 Leetcode 75. Sort Colors 2020.04.14 184
10 Leetcode 2. Add Two Numbers 2020.04.14 194
9 Leetcode 23. Merge k Sorted Lists 2020.04.14 204
8 Leetcode 347. Top K Frequent Elements 2020.04.14 196
7 Leetcode 994. Rotting Oranges 2020.04.14 212
6 Leetcode 3. Longest Substring Without Repeating Characters 2020.04.09 209
5 Leetcode 62. Unique Paths 2020.04.09 206
4 Leetcode 946. Validate Stack Sequences 2020.04.08 194
3 Leetcode 114. Flatten Binary Tree to Linked List 2020.04.06 216
2 Leetcode 430. Flatten a Multilevel Doubly Linked List 2020.04.06 214
1 Leetcode 1055. Shortest Way to Form String 2020.04.06 251
Board Pagination Prev 1 2 3 4 Next
/ 4