Create 791. Custom Sort String (#426)

Author: Chayandas07

791. Custom Sort String

@@ -0,0 +1,23 @@
+class Solution {
+public:
+    string customSortString(string order, string s) {
+        unordered_map<char, int> sCharFreqMp;
+        for(auto currChr : s)sCharFreqMp[currChr]++;
+        string res = "";
+        
+        for(auto currChr : order){
+             if(sCharFreqMp.find(currChr) != sCharFreqMp.end()){
+                 int freq = sCharFreqMp[currChr];
+                 while(freq-->0)res+= currChr;
+                 sCharFreqMp[currChr] = 0;
+             }
+        }
+        for(auto currChr : s){
+            if(sCharFreqMp[currChr] != 0){
+                res += currChr;
+                sCharFreqMp[currChr]--;
+            }
+        }
+        return res;
+    }
+};