Create maximum-number-of-events-that-can-be-attended.cpp

Author: kamyu104

C++/maximum-number-of-events-that-can-be-attended.cpp

@@ -0,0 +1,30 @@
+// Time:  O(r + nlogn), r is the max end day of events
+// Space: O(n)
+
+class Solution {
+public:
+    int maxEvents(vector<vector<int>>& events) {
+        sort(events.begin(), events.end(), greater<vector<int>>());
+        const auto max_day = (*max_element(events.cbegin(), events.cend(),
+                                           [](const auto& a, const auto& b) {
+                                               return a[1] < b[1];
+                                           }))[1];
+        priority_queue<int, vector<int>, greater<int>> min_heap;
+        int result = 0;
+        for (int d = 1; d <= max_day; ++d) {
+            while (!events.empty() && events.back()[0] == d) {
+                min_heap.emplace(events.back()[1]);
+                events.pop_back();
+            }
+            while (!min_heap.empty() && min_heap.top() == d - 1) {
+                min_heap.pop();
+            }
+            if (min_heap.empty()) {
+                continue;
+            }
+            min_heap.pop();
+            ++result;
+        }
+        return result;
+    }
+};