array-of-doubled-pairs

Array of doubled pairs

Problem link

Solutions

Solution.cpp

// https://leetcode.com/problems/array-of-doubled-pairs

class Solution {
 public:
  bool canReorderDoubled(vector<int>& arr) {
    auto comp = [](int a, int b) {
      return (abs(a) == abs(b)) ? (a < b) : (abs(a) < abs(b));
    };
    map<int, int, decltype(comp)> cnt(comp);

    for (auto x : arr) ++cnt[x];
    for (auto& [x, c] : cnt) {
      while (c) {
        --c;
        if (--cnt[x * 2] < 0) return false;
      }
    }
    return true;
  }
};

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