0217-Contains-Duplicate

Problem Description

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.

Solution

bool containsDuplicate(vector<int> &nums) {
  unordered_set<int> st;
  for (int i : nums) {
    if (st.contains(i)) {
      return true;
    }
    st.insert(i);
  }
  return false;
}