Create most-frequent-ids.cpp

Author: kamyu104

C++/most-frequent-ids.cpp

@@ -0,0 +1,42 @@
+// Time:  O(nlogn)
+// Space: O(n)
+
+// heap
+class Solution {
+public:
+    vector<long long> mostFrequentIDs(vector<int>& nums, vector<int>& freq) {
+        vector<long long> result;
+        unordered_map<int, int64_t> cnt;
+        priority_queue<pair<int64_t, int>> max_heap;
+        for (int i = 0; i < size(nums); ++i) {
+            cnt[nums[i]] += freq[i];
+            max_heap.emplace(cnt[nums[i]], nums[i]);
+            while (!empty(max_heap) && max_heap.top().first != cnt[max_heap.top().second]) {
+                max_heap.pop();
+            }
+            result.emplace_back(!empty(max_heap) ? max_heap.top().first : 0);
+        }
+        return result;
+    }
+};
+
+// Time:  O(nlogn)
+// Space: O(n)
+// bst
+class Solution2 {
+public:
+    vector<long long> mostFrequentIDs(vector<int>& nums, vector<int>& freq) {
+        vector<long long> result;
+        unordered_map<int, int64_t> cnt;
+        map<int64_t, int> bst;
+        for (int i = 0; i < size(nums); ++i) {
+            if (--bst[cnt[nums[i]]] == 0) {
+                bst.erase(cnt[nums[i]]);
+            }
+            cnt[nums[i]] += freq[i];
+            ++bst[cnt[nums[i]]];
+            result.emplace_back(rbegin(bst)->first);
+        }
+        return result;
+    }
+};