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程式語言 - LeetCode - C++ - 442. Find All Duplicates in an Array

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題目：


解答：

class Solution {
public:
    vector<int> findDuplicates(vector<int>& nums) {
        vector<int> ans;

        for (int i = 0; i < nums.size(); ++i) {
            int idx = abs(nums[i]) - 1;

            if (nums[idx] < 0) {
                ans.push_back(abs(nums[i]));
            }
            else {
                nums[idx] *= -1;
            }
        }

        return ans;
    }
};