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###### tags: `Leetcode`

# 2568. Minimum Impossible OR

###### Link : https://leetcode.com/problems/minimum-impossible-or/

## 題目
求最小不能被陣列中用位運運算OR求出來的數字
## 程式碼

class Solution {
public:
    //答案必定為最左邊為1 右邊全為0的數字(二進制)
    //example: 100000
    int minImpossibleOR(vector<int>& nums) {
        //紀錄二的指數的出現
        vector<bool> num(log2(*max_element(nums.begin(), nums.end())) + 1, 0);
        for(auto &n : nums){
            //出現2的指數
            if(ceil(log2(n)) == floor(log2(n)))
                num[log2(n)] = true;
        }
        for(int i = 0;i < num.size();++i){//找最小沒出現的指數
            if(num[i] == false)
                return pow(2, i);
        }
        return pow(2, num.size());
    }
};