Merge pull request #65 from InflixOP/patch1

Create #3272. Find the Count of Good Integers.cpp

Author: InflixOP

#3272. Find the Count of Good Integers.cpp

@@ -0,0 +1,64 @@
+class Solution {
+public:
+    long long countGoodIntegers(int n, int k) {
+        unordered_set<string> st;
+
+        int d = (n+1)/2;
+        int start = pow(10,d-1);
+        int end = pow(10,d)-1;
+
+        for(int num = start; num<=end; num++){
+            string leftHalf = to_string(num);
+            string full = "";
+
+            if(n%2 == 0){
+                // n=4 --> 12 21
+                string rightHalf = leftHalf; //12
+                reverse(rightHalf.begin(), rightHalf.end());//21
+                full = leftHalf + rightHalf; //12 21
+            }else{
+                // 123 21
+                string rightHalf = leftHalf.substr(0,d-1);
+                reverse(rightHalf.begin(), rightHalf.end());//21
+                full = leftHalf + rightHalf; //123 21
+            }
+
+            //check div by k then palindrome/good
+            long long number = stoll(full); // 123 21
+            if(number % k !=0)
+                continue;
+            
+            sort(full.begin(), full.end());
+            st.insert(full);
+        }
+
+        //factorial precompute
+        vector<long long> factorial(11,1);
+        for(int i=1;i<11;i++){
+            factorial[i] = factorial[i-1] * i;
+        }
+
+        long long result = 0;
+        //set par jao and saare palindrome ko pakdo
+        for(auto &s: st){
+            // to store the frequency of all
+            vector<int> count(10,0);
+            for(auto &ch: s){
+                count[ch - '0']++;
+            }
+
+            int totalDigits = s.length();
+            int zeroDigits = count[0];
+            int nonZeroDigits = totalDigits- zeroDigits;
+
+            long long perm = (nonZeroDigits * factorial[totalDigits-1]);
+
+            for(int i=0;i<10;i++){
+                perm /= factorial[count[i]];
+            }
+            result +=  perm;
+        }
+        return result;
+
+    }
+};