Create count-pairs-that-form-a-complete-day-ii.cpp

Author: kamyu104

C++/count-pairs-that-form-a-complete-day-ii.cpp

@@ -0,0 +1,16 @@
+// Time:  O(n + 24)
+// Space: O(24)
+
+// freq table
+class Solution {
+public:
+    long long countCompleteDayPairs(vector<int>& hours) {
+        int64_t result = 0;
+        vector<int> cnt(24);
+        for (const auto& x : hours) {
+            result += cnt[((-x % 24) + 24) % 24];
+            ++cnt[x % 24];
+        }
+        return result;
+    }
+};