added SortedPermutatioRank.cpp

Math/SortedPermutationRank.cpp

@@ -0,0 +1,46 @@
+#define mod 1000003
+
+void buildFact(vector<long> &fact,int len){
+    fact.push_back(1);
+    fact.push_back(1);
+    for(int i = 2; i<= len ; i++){
+        fact.push_back((fact[i-1]*i)%mod);
+    }
+}
+
+int Solution::findRank(string A){
+    vector<long> fact;
+    // create a vector filled with factorial value of that index modulated
+    buildFact(fact,A.length());
+
+    // created a sorted version of given string
+    string b = A;
+    sort(b.begin() , b.end());
+
+    // create to Hash to store actual location of each character in sorted manner
+    unordered_map<char , int> pos;
+    for(int i = 0; i<b.length(); i++)
+        pos[b[i]] = i;
+
+    // vector contains actual index for given index.
+    vector<int> v;
+    for(int i = 0; i<A.length(); i++)
+        v.push_back(pos[A[i]]);
+
+    // setting vector for factorial arithmatics
+    for(int i = 0; i<v.size(); i++){
+        for(int j = i+1; j<v.size(); j++){
+            if(v[j] > v[i])
+                v[j]--;
+        }
+    }
+    reverse(v.begin() , v.end());
+
+    // factorial arithmatics
+    long n = 0;
+    for(int i = 0; i < v.size() ; i++){
+        n = (n + v[i]*fact[i])%mod;
+    }
+    n++;
+    return n;
+}