Create 1088.Confusing-Number-II_v2.cpp

Recursion/1088.Confusing-Number-II/1088.Confusing-Number-II_v2.cpp

@@ -0,0 +1,63 @@
+class Solution {
+public:            
+    unordered_map<char,char>Map={{'0','0'},{'1','1'},{'6','9'},{'8','8'},{'9','6'}};
+    int count = 0;    
+    int N;
+    string n;
+
+    long perm(int l)
+    {
+        return 4*pow(5,l-1);
+    }
+
+    long symmetric(int l)
+    {
+        if (l%2==0)        
+            return 4*pow(5,l/2-1);
+        else
+            return 4*pow(5,l/2-1)*3;
+    }
+
+    int confusingNumberII(int N) 
+    {        
+        this->N = N;
+        n = to_string(N);
+
+        for (int l=1; l<n.size(); l++)
+        {
+            count += perm(l) - symmetric(l);
+        }
+
+        for (long x: {1,6,8,9})
+            dfs(x,1);
+        return count;
+    }
+
+    void dfs(long num, int k)
+    {
+        if (k==n.size())
+        {
+            if (num>N) return;
+            if (isConfusing(num)) count++;
+            return;
+        }
+
+        for (auto x:{0,1,6,8,9})        
+            dfs(num*10+x, k+1);
+    }
+
+    bool isConfusing(int num)
+    {
+        string s = to_string(num);
+        int i=0;
+        int j=s.size()-1;
+        while (i<=j)
+        {
+            if (Map[s[i]]!=s[j])
+                return true;
+            i++;
+            j--;
+        }                
+        return false;
+    }
+};