message: Update describe-the-painting.cpp
diff: class Solution {
  public:
  vector<vector<long long>> splitPainting(vector<vector<int>>& segments) {
  - unordered_map<int, int64_t> events;
  + unordered_map<int, int64_t> counts;
  for (const auto& s : segments) {
  - events[s[0]] += s[2];
  - events[s[1]] -= s[2];
  + counts[s[0]] += s[2];
  + counts[s[1]] -= s[2];
  }
  - vector<pair<int, int64_t>> points(cbegin(events), cend(events));
  + vector<pair<int, int64_t>> points(cbegin(counts), cend(counts));
  sort(begin(points), end(points));
  vector<vector<long long>> result;
  