#include "leetcode.h" class Solution { public: vector findOriginalArray(vector &changed) { int count[100001] = {}, i = 0; vector ans; for (auto n : changed) ++count[n]; for (int i = 0; i <= 50000; ++i) if (count[i]) { if (--count[i * 2] < 0 || --count[i] < 0) return {}; ans.push_back(i--); } return accumulate(begin(count) + 50000, end(count), 0ll) ? vector() : ans; } };