Create minimum-domino-rotations-for-equal-row.cpp

Author: kamyu104

C++/minimum-domino-rotations-for-equal-row.cpp

@@ -0,0 +1,46 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int minDominoRotations(vector<int>& A, vector<int>& B) {
+        set<int> intersect{A[0], B[0]};
+        for (int i = 1; i < A.size(); ++i) {
+            const set<int> s1{A[i], B[i]};
+            const auto s2 = move(intersect);
+            set_intersection(s1.cbegin(), s1.cend(),
+                             s2.cbegin(), s2.cend(),
+                             inserter(intersect, intersect.begin()));
+        }
+        if (intersect.empty()) {
+            return -1;
+        }
+        auto x = *intersect.begin();
+        return min(A.size() - count(A.begin(), A.end(), x),
+                   B.size() - count(B.begin(), B.end(), x));
+    }
+};
+
+// Time:  O(n)
+// Space: O(1)
+class Solution2 {
+public:
+    int minDominoRotations(vector<int>& A, vector<int>& B) {
+        unordered_set<int> intersect{A[0], B[0]};
+        for (int i = 1; i < A.size(); ++i) {
+            const unordered_set<int> s1{A[i], B[i]};
+            const auto s2 = move(intersect);
+            copy_if(s1.cbegin(), s1.cend(),
+                    inserter(intersect, intersect.begin()),
+                    [&s2](const int x) {
+                        return s2.count(x) > 0;
+                    });
+        }
+        if (intersect.empty()) {
+            return -1;
+        }
+        auto x = *intersect.begin();
+        return min(A.size() - count(A.begin(), A.end(), x),
+                   B.size() - count(B.begin(), B.end(), x));
+    }
+};