Create code.cpp

351.android_unlock_patterns/code.cpp

@@ -0,0 +1,30 @@
+class Solution {
+public:
+    int numberOfPatterns(int m, int n) {
+        int visited = 0;
+        int ans = 0;
+        ans += check(visited, 0, 0, 1, m, n) * 4;
+        ans += check(visited, 0, 1, 1, m, n) * 4;
+        ans += check(visited, 1, 1, 1, m, n);
+        return ans;
+    }
+
+    int check(int &visited, int x, int y, int count, int m, int n) {
+        if (count == n) return 1;
+        int myans = 0;
+        if (count >= m) myans++;
+        visited += 1 << (x * 3 + y);
+        for (int i = 0; i < 3; i++) {
+            for (int j = 0; j < 3; j++) {
+                if (!(visited & (1 << (i * 3 + j)))) {
+                    if (abs(x - i) == 2 && abs(y - j) == 2 && !(visited & (1 << 4))) continue;
+                    if (abs(x - i) == 2 && y == j && !(visited & (1 << (3 + y)))) continue;
+                    if (abs(y - j) == 2 && x == i && !(visited & (1 << (3 * x + 1)))) continue;
+                    myans += check(visited, i, j, count + 1, m, n);
+                }
+            }
+        }
+        visited -= 1 << (x * 3 + y);
+        return myans;
+    }
+};