Contains Duplicate Problem


Description

LeetCode Problem 217.

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

Example 1:

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Input: nums = [1,2,3,1]
Output: true

Example 2:

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Input: nums = [1,2,3,4]
Output: false

Example 3:

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Input: nums = [1,1,1,3,3,4,3,2,4,2]
Output: true

Constraints:

  • 1 <= nums.length <= 10^5
  • -10^9 <= nums[i] <= 10^9


Sample C++ Code

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class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        bool distinct = true;
        map<int, int> ht;
        for (int i = 0; i < nums.size(); i ++) {
            int n = nums[i];
            if (ht.find(n) == ht.end())
                ht[n] = 0;
            ht[n] ++;
            if (ht[n] > 1) {
                distinct = false;
            }
        }
        return !distinct;          
    }
};




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