Create find-missing-observations.cpp

Author: kamyu104

C++/find-missing-observations.cpp

@@ -0,0 +1,47 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    vector<int> missingRolls(vector<int>& rolls, int mean, int n) {
+        static const int MAX_V = 6;
+        static const int MIN_V = 1;
+        
+        const int total = accumulate(cbegin(rolls), cend(rolls), 0);
+        const int missing = mean * (n + size(rolls)) - total;
+        if (missing < MIN_V * n || missing > MAX_V * n) {
+            return {};
+        }
+        const int q = missing / n;
+        const int r = missing % n;
+        vector<int> result(n);
+        for (int i = 0; i < size(result); ++i) {
+            result[i] = q + int(i < r);
+        }
+        return result;
+    }
+};
+
+
+// Time:  O(n)
+// Space: O(1)
+class Solution2 {
+public:
+    vector<int> missingRolls(vector<int>& rolls, int mean, int n) {
+        static const int MAX_V = 6;
+        static const int MIN_V = 1;
+        
+        const int total = accumulate(cbegin(rolls), cend(rolls), 0);
+        const int missing = mean * (n + size(rolls)) - total;
+        if (missing < MIN_V * n || missing > MAX_V * n) {
+            return {};
+        }
+        const int q = (missing - MIN_V * n) / (MAX_V - MIN_V);
+        const int r = (missing - MIN_V * n) % (MAX_V - MIN_V);
+        vector<int> result(n);
+        for (int i = 0; i < size(result); ++i) {
+            result[i] = (i < q) ? MAX_V : ((i == q) ? MIN_V + r : MIN_V);
+        }
+        return result;
+    }
+};