28 lines
604 B
C++
28 lines
604 B
C++
#include <vector>
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#include <iostream>
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#include <unordered_set>
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/**
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* 136. Single Number
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* Given a non-empty array of integers nums, every element appears twice except for one. Find that single one.
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* You must implement a solution with a linear runtime complexity and use only constant extra space.
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*/
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class Solution {
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public:
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static int singleNumber(const std::vector<int>& nums) {
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std::unordered_set<int> s;
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for (int i : nums)
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if (s.count(i))
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s.erase(i);
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else
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s.insert(i);
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return *s.begin();
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}
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};
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int main() {
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std::cout << Solution::singleNumber({4,1,2,1,2});
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return 0;
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}
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