Create number-of-flowers-in-full-bloom.cpp

Author: kamyu104

C++/number-of-flowers-in-full-bloom.cpp

@@ -0,0 +1,48 @@
+// Time:  O(nlogn + mlogn)
+// Space: O(n)
+
+// line sweep, binary search
+class Solution {
+public:
+    vector<int> fullBloomFlowers(vector<vector<int>>& flowers, vector<int>& persons) {
+        map<int, int> cnt;
+        for (const auto& flower : flowers) {
+            ++cnt[flower[0]];
+            --cnt[flower[1] + 1];
+        }
+        vector<int> prefix = {0};
+        vector<int> events;
+        for (const auto& [k, v] : cnt) {
+            events.emplace_back(k);
+            prefix.emplace_back(prefix.back() + v);
+        }
+        vector<int> result;
+        for (const auto& t : persons) {
+            int i = distance(cbegin(events), upper_bound(cbegin(events), cend(events), t));
+            result.emplace_back(prefix[i]);
+        }
+        return result;
+    }
+};
+
+// Time:  O(nlogn + mlogn)
+// Space: O(n)
+// binary search
+class Solution2 {
+public:
+    vector<int> fullBloomFlowers(vector<vector<int>>& flowers, vector<int>& persons) {
+        vector<int> starts, ends;
+        for (const auto& flower : flowers) {
+            starts.emplace_back(flower[0]);
+            ends.emplace_back(flower[1] + 1);
+        }
+        sort(begin(starts), end(starts));
+        sort(begin(ends), end(ends));
+        vector<int> result;
+        for (const auto& t : persons) {
+            result.emplace_back(distance(cbegin(starts), upper_bound(cbegin(starts), cend(starts), t)) - 
+                                distance(cbegin(ends), upper_bound(cbegin(ends), cend(ends), t)));
+        }
+        return result;
+    }
+};