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
Approach #1: C++.
class Solution {
public:
bool containsDuplicate(vector<int>& nums) {
unordered_map<int, int> mp;
for (int i = 0; i < nums.size(); ++i) {
mp[nums[i]]++;
if (mp[nums[i]] > 1) return true;
}
return false;
}
};
Approach #2: Java.
class Solution {
public boolean containsDuplicate(int[] nums) {
Set<Integer> set = new HashSet<Integer>();
for (int i : nums)
if (!set.add(i))
return true;
return false;
}
}
Approach #3: Python.
class Solution(object):
def containsDuplicate(self, nums):
"""
:type nums: List[int]
:rtype: bool
"""
return len(nums) != len(set(nums))
| Time Submitted | Status | Runtime | Language |
|---|---|---|---|
| a few seconds ago | Accepted | 28 ms | python |
| a few seconds ago | Accepted | 13 ms | java |
| 4 minutes ago | Accepted | 24 ms | cpp |
原文：https://www.cnblogs.com/ruruozhenhao/p/9963361.html